nervures, the anterior longest, narrow at the base and dilated at the extremity; the abdomen begins between the 2 posterior legs; the feet are long and slender. It is difficult to detect the sexes except by the ovipositor with which the females are provided; this instrument is short or long according as the eggs are to be deposited in the bodies of caterpillars on the surface of the ground or to be thrust down into their living nidus through a nest or deep crevice; in the former it is retractile and lodged in a groove on the under side of the body, in the latter often longer than the body, consisting of a central oviduct and 2 lateral protecting appendages coming from the last abdominal segment. The eggs are hatched in the body of the larva, and the young consume the fatty matters in the interior of the victim, without injuring the vital organs; many eggs are often deposited within the same larva; the young undergo transformation within the living insect, or eat their way through the skin and spin their pupa cases on the outside, from which after a time they come out perfect insects. The larvæ selected for this deposition are so enfeebled by the parasites that they perish without going into the pupa state. A common example is met with in the large green caterpillar, with a horn on the last segment, generally called the potato worm; this is a favorite nidus for the eggs of a minute black ichneumon fly; the young, hatched within its body and devouring its substance, eat through the skin, and spin their pupa cases so thick upon the outside as almost to cover the back and sides of this 4-inch caterpillar; each case is attached to the skin by a short delicate filament, and the place of exit of each larva is indicated by a black dot; this caterpillar is often seen crawling about and eating, almost covered with a colony of these tiny silvery white pupa cases, from which in about a week the shining ichneumon flies appear; the caterpillar does not enter the pupa state, but dies exhausted. These flies are generally rapid in their movements, and are taken with difficulty except when depositing their eggs; they occur in flowers, on trees and walls, in houses, and wherever the desired larvæ are found. The perfect insects live upon the pollen and honey of flowers, and do not attack other insects except to make a deposit of eggs; they are of all sizes, from a fraction of a line to more than an inch long; e species are exceedingly numerous, there being about 1,500 in Europe alone. The larvæ are without feet, parasitical and carnivorous. The chalcidians, allied to the ich neumon flies, are extremely small; they puncture the eggs of other insects and deposit their own tiny ones in them. We can hardly estimate the benefits conferred upon man by these apparently insignificant insects; their instincts lead them to do for man's advantage what all his contrivances could not effect; to mention only a few destructive insects kept in check by them, the best known are the pine weevils, lackey caterpillars, the grubs of many wood

eaters of their own order, the gall insects, the Hessian fly, and hosts of others which would overrun the forests and fields were it not for the agency of these diminutive creatures.

ICHNOLOGY (Gr. xvos, a footprint, and Aoyos, discourse), the name applied to the modern science of fossil footprints, or ichnolites. See FOSSIL FOOTPRINTS, and HITCHCOCK, EDWARD. ICHTHYOLOGY (Gr. xous, a fish, and Aoyos, discourse), the branch of zoology which treats of fishes, the lowest of the great divisions of the vertebrated animals. The class of fishes cannot be said to have been arranged in a strictly natural manner by any systematist, and such an arrangement is impossible until their external and internal structure and embryonic development are better understood; and until zoologists are better agreed as to what constitutes family, ordinal, generic, and specific characters, little harmony of arrangement can be expected. Most classifications of fishes up to the time of Cuvier (including his) were based on the organs of locomotion and the external integument; after him appeared the anatomical arrangement by J. Müller, and one is expected from Prof. Agassiz founded on anatomical structure and embryological development. The older systems were very imperfect from the ignorance of fossil forms, which supply many links otherwise wanting in the chain of ichthyological characters. Aristotle, in the 4th century B. C., first. reduced ichthyology, as he did the other branches of zoology, to scientific form; he was well acquainted with the structure and external characters of fishes, which he distinguishes from cetaceans, laying special stress upon the organs of respiration and locomotion and the scaly covering; he gives the names of 117 species, entering into interesting details on their habits. Several of Aristotle's disciples added important facts to those of their master. For want of patrons like Alexander, the science of experimental natural history rapidly fell into decline, and the system of Aristotle received no amplification, and hardly any attention; the Romans aided in nothing the progress of ichthyology, and Pliny's writings are mere compilations from Aristotle and his pupils. This system of compilation without observation prevailed until the middle of the 16th century, when Belon, Rondelet, and Salviani laid the foundations of modern ichthyology. Belon gives rude figures of 110 species, Salviani excellent engravings on copper of 99, and Rondelet woodcuts of 234 species, in all three mostly fishes of the Mediterranean. Gesner in the same century borrowed the descriptions of the last mentioned authors, and added some of his own in his Historia Animalium (1551-'6), all arranged in alphabetical order without any attempt at method, embracing however many foreign fishes. Numerous voyages of discovery to the East Indies and America made naturalists acquainted with many new forms, and the proceedings of the learned societies in all countries of Europe were filled with anatomical and other descrip

tions of new and strange fishes. Ray and his pupil Willughby, English naturalists of the 17th century, in their Historia Piscium (1686), gave the first attempt at a natural classification of fishes, founded upon the consistence of the skeleton, the form, the teeth, presence or absence of ventral fins, number of dorsals, and character of the fin rays. They divided fishes into cartilaginous and osseous; the former were either longi (sharks) or lati (rays); the latter were plani (flat fishes) or non plani (ordinary fishes); the non plani were either anguilliformes (eel-like), or with a more contracted body with or without ventrals; the fishes with ventrals were divided into malacopterygii (softrayed), with 1, 2, or 3 dorsals, and acanthopterygii (spiny-rayed), with 1 or 2 dorsals. Though their genera are not well defined, the species are so well described that it is generally easy to refer them to their proper place in subsequent systems; the whole number of species is 420. The 2d volume consists of well executed, tolerably accurate plates. This work forms an epoch in the history of ichthyology, which from this time began to assume a methodical arrangement. Passing over Sloane, Catesby, Ruysch, Kämpfer, Plumier, and many scientific voyagers of this period, we come to Artedi in the first third of the 18th century. This Swedish naturalist completed the scientific classification of fishes, commenced by Willughby and Ray, defining genera and giving them appropriate names. In his Philosophia he divides the class into 4 orders, founded on the consistence of the skeleton, the branchial coverings, and the nature of the fin rays, as follows: 1, malacopterygians; 2, acanthopterygians; 3, branchiostegous fishes; and 4, chondropterygians (sharks, rays, and sturgeons). He made a 5th, including cetaceans, which is inadmissible, and the 3d is badly characterized; the 3 others are to a certain degree natural. In his Genera Piscium he gives names and distinctive characters of 45 genera, founded on the number of branchiostegous rays (of which he was the first to see the value), on the position and number of the fins, on the parts supplied with teeth, on the form of the scales, and on the shape of the stomach and cæcal appendages; most of these genera stand at the present day. In his Synonymia Piscium he gives the synonymy of 274 species. Though borrowing much from Willughby, Artedi added much of the greatest value; his works were published after his death by Linnæus, his early friend, at Leyden, in 1738.-Linnæus, in the 1st edition of the Systema Natura (1735), followed Artedi; but in the next (1740) he began to give the number of the fin rays, a method of distinguishing since found of great value. In his 10th edition (1758) he trusted to his own knowledge, creating a new system, defining genera more clearly, and using a scientific nomenclature; the most important change was in removing cetaceans from the class of fishes, in which after the time of Aristotle they had been placed, and in uniting them with viviparous

quadrupeds into the class mammalia. Brisson, in 1756, had already separated them from fishes. Linnæus, however, committed the error of placing the chondropterygians among reptiles, under the title of amphibia nantes, to which in the 12th edition (1766) he had added the branchiostegi of Artedi (ostracion, lophius, tetrodons, &c.). He also suppressed the division of fishes according to the nature of the fin rays, and substituted one founded on the presence or absence of the ventral fins and their position in reference to the pectorals, a method which violates many of the true relations of these animals. Before this time Gronovius had published his Museum Ichthyologicum (Leyden, 1754-'6), describing 53 genera according to the system of Artedi, and his Zoophylacium (1763), with 78 genera, divided into chondropterygii, branchiostegi, and branchiales, arranged according to the position of the ventrals and the number and character of the dorsals. Linnæus in his 12th edition describes 414 species, some of which were taken from Gronovius, from descriptions of various cabinets of his time, and from voyages and scientific journals. In the system of Klein, which Linnæus must have purposely ignored in a spirit of retaliation, as contained in his Missus Historia Naturalis Piscium promovenda (1740-'49), 61 genera are described; the divisions are made according to the shape of the body and head, and the number of the dorsals and branchial openings, and the openness of the latter; it contains some new species, good figures, and true generic groups. Though Linnæus neglected some of the genera of his contemporaries, and distributed his orders in an unnatural manner, describing only 480 species, his precision of definition and the excellence of his binary nomenclature were of great advantage to the progress of ichthyology, and his division into apodes, jugulares, thoracici, and abdominales for a long time held its place in the science. Linnæus gave an impetus to the study of natural history, which resulted in making it interesting to all classes, and in inspiring kings with a desire to extend its domain; national expeditions were fitted out by England, France, Denmark, and Russia, which came back laden with treasures of the deep for naturalists; among the workers in this great field we can only mention the names of Commerson, Sonnerat, Pennant, Banks, Solander, the Forsters, Forskal, Steller Otho Fabricius, O. F. Müller, and Thunberg; the scientific journals teemed with descriptions of new species of fishes from all parts of the globe.-The next great contributor to ichthyology was the German naturalist Bloch, whose celebrated work on the "Natural History of Fishes" consists of two parts essentially distinct; the first, the "Economic History of the Fishes of Germany," appeared at Berlin in 1782-'4, in 3 vols. 4to., with 108 folio plates; the second, the "History of Foreign Fishes," in 1785-'95, in 9 vols. 4to., with 324 folio plates; both were translated into French in a few years after each volume ap

peared. Of German fishes he describes 115 species, mostly observed by himself. Little conversant with the anatomy of fishes, some of his genera are based on purely artificial characters, while others are remarkably correct. He follows the method of Linnæus, bringing back the amphibia nantes, however, into the class of fishes, and dividing them, with Artedi, into branchiostegi and chondropterygii. Toward the end of his life he prepared a general ichthyological system, which was published after his death, edited by Schneider, in 1801, in 1 vol. 8vo. with 110 plates; in this he conceived the singular idea of classifying fishes according to the number of the fins, and on this principle makes 11 orders, adopting the Linnæan divisions of jugulares, thoracici, abdominales, and apodes; these orders are: 1, hendecapterygii; 2, decapterygii; 3, enneapterygii; 4, octopterygii; 5, heptapterygii; 6, hexapterygii; 7, pentapterygii; 8, tetrapterygii; 9, tripterygii; 10, dipterygii; and 11, monopterygii. This artificial system leads to the approximation in the same order of fishes the most widely separated, and divides others most nearly related; the chief merit consists in the number of new species described, the genera being 113, and the species 1,519.The 13th or Gmelin's edition of Linnæus appeared in 1788-'90, a mere compilation by a person but little acquainted with natural history, containing a confused account of the discoveries in ichthyology for the preceding 25 years, and copying the errors as well as the facts of his several authorities; it is valuable chiefly as a book of quotations, and as indicating to the student the original sources of information on his science; only about 780 undoubted species are described, and only 5 genera are added to the 61 of Linnæus.-Comparative anatomy had made considerable progress toward the end of the 18th century, when Lacépède began his researches in 1798-1803; amid the terrors of the French revolution, shut off from communication with foreign ichthyologists, and deprived of new accessions from abroad, he was forced to work principally upon old materials without the opportunity to detect the errors of his predecessors. He divides the class into cartilaginous and osseous fishes, in each of which sub-classes he makes 4 divisions: 1, with neither opercula nor branchial membrane; 2, without opercula, and with a branchial membrane; 3, with opercula and without branchial membrane; and 4, with both opercula and branchial membrane. In each of the 8 divisions he adopts the orders of apodes, jugulares, thoracici, and abdominales, according to the absence of ventrals, or their position on the throat, thorax, or abdo

men.

The natural history of fishes in Sonnini's Buffon (1803-4) is essentially a copy of Lacépède without acknowledgment. These works of Bloch and Lacépède supplied the principal foundation for most subsequent systems. The classification of M. Duméril, in his Zoologie analytique (1806), resembles that of Lacépède, inasmuch as it lays stress upon the supposed absence

of opercula and branchial rays and the position of the ventral. In the cartilaginous fishes he makes the orders: 1, trematopnés, including the cyclostome and plagiostome families; 2, chismopnés, and 3, eleutheropomes, each with a single family; and 4, teleobranches, with 3 families. In the osseous fishes are ranked: 5, holobranches, with 23 families of the most common species; 6, sternoptyges, 7, cryptobranches, and 8, ophichtites, each with a single family. He gives in all 212 genera. In 1810 Rafinesque published at Messina a list of Sicilian fishes arranged according to a natural order; the species are 390, of which about 180 are described as new; the system is essentially that of Lacépède, except that the cartilaginous are mixed in with osseous fishes, according to the opercular and branchial characters; he makes 71 orders, generally without regard to natural affinities, though some of the ideas are original and deserve attention. Pallas, in the 3d volume of the Zoographia RussoAsiatica (1811), gives a list of 240 species, distributed into 38 genera, with the exception of 3 taken from Linnæus; he makes 2 orders, spiraculata or chondropterygians, and branchiata, forming with reptiles (pulmonata) the class monocardia (single-hearted or cold-blooded animals). In 1815 Rafinesque published a 2d ichthyological system in his "Analysis of Nature, or Tableau of the Universe" (1 vol. 8vo., Palermo); on the principles of Lacépède he obtains the orders deripia, thoraxipia, gastripia, apodia, eltropomia, chismopnea, and tremapnea, subdivided into 30 families, each comprising 2 or 3 sub-families, and including in all 377 genera. Though containing many errors, this system is valuable for several true affinities between fishes before and since regarded as widely separated, as for instance that of the polypterus with the sturgeon family.-De Blainville in 1816 (Journal de physique, vol. lxxxiii.) published a classification in which fishes are divided into gnathodontes or osseous and dermodontes or cartilaginous, the latter distinguished by having teeth adherent only to the skin; the former include the heterodermes or branchiostegi, and the squammodermes or common fishes; in the subdivisions the Linnæan character of the position of the ventrals is adopted, and the families are established principally on the form of the body; it does not employ the Lacepèdean characters taken from the opercula and branchial rays.-Cuvier, in 1817, in his Règne animal, divides fishes into chondropterygians and osseous. The former contain the families of suckers (lampreys), selachians (sharks and rays), with fixed branchia, and the sturionians (sturgeons), with free branchiæ. In the osseous fishes he suppresses the branchiostegi, forming of a portion of them the order plectognathi, from a peculiar mode of articulation of the jaws, including the families gymnodonts, scleroderms, and lophobranchs. The remaining osseous fishes he separates into the orders malacopterygians and acanthopterygians, after Artedi, according as the rays of the dorsal fin

are soft or spiny. The soft-rayed order he distributes into families, according to the Linnæan method of the position of the ventrals, disregarding entirely characters drawn from the opercula and branchial rays; in the abdominal fishes are the salmones (salmons), clupes (herrings), esoces (pikes), cyprini (carps), and siluroides (catfish); in the sub-brachians are the gadoides (cod), flatfishes, and discoboli (lump fishes); in the apodals are the anguilliformes (eel-like fishes). The spiny-rayed fishes form a single order, with the families tænioids (ribbon fishes), gobioids (blennies and gobies), labroids (bass), percoids (perches, a very extensive family), scomberoids (mackerel-like, also numerous), squammipennes (chaetodons, &c.), and the flutemouths (fistularia, &c.). He thus makes in all 22 families, founded on direct observation and comparison, and not simply compiled from previous authorities.-Goldfuss ("Manual of Zoology"), in 1820, adopted the 4 orders of Gmelin, giving to them Greek names, and subdividing them into 4 families, each according to the shape of the head, mouth, or body, or other external character. The abdominal fishes he calls gasteropterygii, with the families leptocephala, rhynchocephala, aptocephala, and platycephala; the apodals are styled pteropterygii, with the families ophioidei, enchelioidei, ryphonoti, and macrorhynchi; the jugulares and thoracici are united into the sternopterygii, with the families orthosomata, taniosomata, leptosomata, and cephalotes; the branchiostegi and cartilaginous fishes form the chondropterygii, with the families microstomata, cyclostomata, macrostomata, and plagiostomata.-Risso (Histoire naturelle de l'Europe méridionale, vol iii., 1827) takes as the basis of his classification the apodes, jugulares, thoracici, and abdominales of Linnæus, adding the orders plectognathes and lophobranches of Cuvier, and making of the chondropterygians two orders according as the gills are fixed or free; the ordinary fishes he divides into malacopterygians and acanthopterygians.Thus far the systems have been little more than repetitions of the combinations of Artedi, Linnæus, and Lacepède. Comparative and philosophical anatomy began to be studied with zeal from the beginning of the 19th century. Oken, Carus, Geoffroy St. Hilaire, Spix, Weber, Van der Hoeven, Meckel, Everard Home, Hunter, Tiedemann, and others, wrote upon different portions of the structure of fishes, and their results began to modify ichthyological classifications. Before mentioning the anatomical and embryological systems, the classification adopted in the Histoire naturelle des Poissons, by Cuvier and Valenciennes, beginning in 1828 and coming down to the present time, may be alluded to. In this, fishes are divided into osseous and cartilaginous, the latter (or chondropte rygians) including the families sturionians, plagiostomes, and cyclostomes. The osseous fishes have the branchiæ pectinated or laminated, with the exception of the lophobranchs, which have them in the form of tufts: all the acanthopte

rygians have the upper jaw free, including 13 families, and all the malacopterygians except the scleroderms, gymnodonts, and lophobranchs; the malacopterygians are divided into abdom inals, sub-brachians, and apodes. Cuvier had very abundant materials at his command, embracing the collections of Péron, and those of the expeditions under Baudin, Freycinet, Duperrey, Dumont d'Urville, and other French naval officers.-Oken, in his "Physiophiloso phy" (Ray society edition), calls the class glossozoa, as those animals in which a true tongue makes its appearance for the first time, and 08teozoa, because in them also the bony system first appears. He makes 4 divisions, the cartilaginous apodal and jugulares, thoracici, and abdominales, the first 2 having an irregular and the last 2 a regular body. Of the irregular fishes he makes 2 orders: I. The intestinal, protozooid fishes, with the mouth round and without maxillæ, or disproportionately narrow and wide, including the families: 1, infusorial fishes or lampreys; 2, polypary fishes (narrow-mouthed); and 3, acalephoid, or wide-mouthed (frog fishes). II. Vascular, conchozooid fishes, with: 4, mussel fishes (eels); 5, snail fishes (haddocks); and 6, kraken fishes (gobies and trigla). In the regular fishes are 3 orders: III. Pulmonary or aneyliozooid fishes, with: 7, worm fishes (tunnies); 8, crustacean fishes (labrida, &c.); and 9, ptilotoid fishes (perch). IV. Sarcose fishes, with: 10, typical fishes, or carps; 11, reptilian fishes (salmons); and 12, ornithic fishes (herrings and pikes). V. Sensorial fishes, with the last family: 13, thricozooid fishes (sharks, rays, sturgeons, &c.), the highest of the class.-Carus arranges fishes in his 3d circle, cephalozoa, and in his 4th class, cephalo-adoiozoa; his orders are: 1, cyclostomata, related to articulata, as petromyzon and myxine; 2, orthosomata apoda, as murana; 3, orthosomata catapoda, with the sub-orders sternopterygii (perch, cod, mackerel, &c.) and gasteropterygii (pike, salmon, herring, &c.); 4, microstomata, as ostracion, diodon, pegasus, acipenser; and 5, plagiostomata, related to reptiles, including the sharks and rays.Among the systems based upon that of Cuvier are those of Bonaparte, Swainson, Straus-Durckheim, and Rymer Jones. The classification of C. L. Bonaparte (Rome, 1831) comprised the orders: I., acanthopterygii,with 17 families; II, malacopterygii, with 12 families; III., plectognathi, with 2 families; and IV., cartilaginei, with 5 families; including in all nearly 3,600 species. The principal improvement on the system of Cuvier is in the series in which the genera are placed. Swainson ("Monocardian Animals," in Lardner's " Cyclopædia," 1838-'9), true to his quinary system, divides fishes into the 5 orders acanthopteryges, malacopteryges, cartilagines, plectognathes, and apodes; the 1st and 2d typical forms, and the most highly organized, correspond in his circles to quadrupeds and birds, lizards and snakes, insessorial and rapacious birds, monkeys and carnivora respectively; the 3d, of large size, mostly viviparous,

and with a broad and depressed snout, represent reptiles, saurians, swimming birds, and cetaceans; the 4th, with small eyes situated far back, without true teeth or scales, with sharp jaws, and oval thick body armed with mail and semi-aquatic, he considers analogous to amphibians, chelonians, wading birds, and rodents; while the 5th, with the limbs smaller or absent and tail very long, correspond to fish, chameleons, rasorial birds, and hoofed quadrupeds in their respective circles. Straus-Durckheim (Traité d'anatomie comparative, Paris, 1843) adopts the 8 orders of Cuvier, but subdivides the chondropterygians with fixed branchiæ into 3 orders, and separates the sharks as the order selaciens, the rays as the order batoides, and the cyclostomes as the order galexiens (from Gr. yaλeos, lamprey), the term cyclostoma having been used for a gasteropod mollusk; he thus makes 10 orders. Rymer Jones (in the article "Pisces," in the "Cyclopædia of Anatomy and Physiology," 1847) adopts a modification of Cuvier's system. He makes 3 divisions: I., chondropterygii or cartilaginous fishes, with orders plagiostomata (with fixed branchia) and sturionida (with free branchia); II., osteopterygii or bony fishes, with orders acanthopterygii, malacopterygii abdominales, M. subbrachiales, M. apodes, lophobranchii, and plectognathi; III., dermapterygii, with skeleton cartilaginous or membranous, and with orders cyclostomata (lampreys) and branchiostomata.-About 1830 Prof. Agassiz, principally from the study of fossil fishes, established a classification based on the characters of the scales, as follows: order 1, placoids, corresponding to the cartilaginous fishes of authors, excluding, however, the sturgeons; 2, ganoids, including the sturgeons, and especially the fossil genera with enamelled scales; 3, ctenoids, comprising bony fishes with scales pectinated on the posterior border, and corresponding generally to the acanthopterygians of Artedi, exclusive of the scomberoids, labroids, and pleuronectes; 4, cycloids, including the malacopterygians with the above exceptions, and exclusive of the blennioids and lophioids. This system, now abandoned as an exclusive one by its author. from its placing too much stress on external characters, was valuable as connecting in a continuous series living and fossil fishes, and led to the discovery of many important relations between the scales and the internal organs.-The system of Johannes Müller, as given in the Berlin "Transactions" for 1844, derives its characters from anatomical structure, leading often to combinations without regard to zoological differences. He makes 6 sub-classes: I., dipnoi; II., teleostei; III., ganoidei; IV., elasmo-branchii or selachii; V., marsipobranchii or cyclostomi; VI., leptocardii. The first includes the order sirenoidei, with the family of the same name, embracing lepidosiren, &c. The 2d, including the osseous fishes generally, has the following orders: 1, acanthopteri, with 15 families, like perches, &c.; 2, anacanthini, with the sub-orders subVOL. IX.-29

brachii (gadoids and flat fishes) and apodes, with family ophidini; 3, pharyngognathi, with the sub-orders of spiny-rayed (labroids and chromids) and soft-rayed scomberesoces; 4, physostomi with sub-orders abdominales, 11 families (siluroids, salmons, herrings, &c.), and apodes, with 3 families of eel-like fishes; 5, plectognathi, with 3 families (ostracions, &c.); and 6, lophobranchii, with a family of the same name, including hippocampus, &c. The 3d sub-class has the orders: 1, holostei, with families lepidosteini and polyptering; and 2, chondrostei, with families acipenserini and spatularia. The 4th has the orders: 1, plagiostomi, with the sub-orders squalide or sharks, 10 families, and rajida or rays, 6 families; and 2, holocephali, with the family chimæra. The 5th comprises the orders: 1, hyperoartii, with family petromyzonini; and 2, hyperotreti, with family myxinoidei. The 6th and last sub-class includes the order amphioxini, with the family of that name. Siebold and Stannius adopt this classification in their "Comparative Anatomy;" and a slight modification of it may be found in the 3d volume of the "Organic Nature" in Orr's "Circle of Sciences," 1855. Owen's classification, mentioned below, and adopted by Sir John Richardson in the article "Ichthyology" of the "Encyclopædia Britannica," is based partly on that of Müller.-Vogt, in his Zoologische Briefe (1851), divides fishes into the orders leptocardia, cyclostomata, selachia, ganoidea, and teleos tia. Van Beneden's embryological system is nearly the same, at the date of 1855; his orders are plagiostomi, ganoidei, teleostei, cyclostomi, and leptocardii. Van der Hoeven's classification, at about the same date (as given in the English translation of his "Handbook of Zoology," 1858), makes fishes the 14th class of the animal kingdom, and divides them into 5 sections, with 11 orders and 46 families. The sections are: I. Dermopterygii, with the orders: 1, leptocardii, and family amphioxini; 2, cyclostomi, with the myxinoid and petromyzont families. II. Chondropterygii, with orders: 3, desmiobranchii or plagiostomes (rays and sharks); 4, eleutherobranchii, with the chimæroid family. III. Ganolepidoti, with orders: 5, chondrostei (sturgeons), and 6, ganolepidoti (lepidosteus and extinct sauroids.) IV. Osteopterygii, with orders: 7, lophobranchii, and family of the same name; 8, pectognathi, with gymnodont and scleroderm families; 9, malacopterygii, with 16 soft-rayed families; and 10, acanthopterygii, with 18 spiny-rayed families. V. Protopteri, with order 11, containing the family sirenoidei (lepidosiren). Milne-Edwards, in his Cours élémentaire d'histoire naturelle (1855), divides fishes into osseous and cartilaginous; the former includes the orders acanthopterygii, abdominales, subbrachii, apodes, lophobranchii, and plectognathi; and the latter, the orders sturiones, selachii, and cyclostomi.-Owen's classification is as follows, taken from his "Lectures on Comparative Anatomy" (1855): order I., dermopteri, with the sub-orders pharyngobran