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base. In the fragments removed very cautiously with a knife, I could recognise what appeared to be portions of simple tentacula, muscular fibres and a fibrous matrix, brown pigment cells, the usual yellow or amber-tinted spherical globules of the subjacent parts, and ciliated epithelium, from the lining of the common cavity. The analogy of other cases suggests the probability that the tentacula correspond with the outer whorl of loculi.

The most remarkable circumstance connected with these polyps, is the invariable presence of a little solitary Sipunculus in a beautifully excavated burrow at the base of the corallum. The uniform position of the opening and sinistral direction of this burrow, first observed in dead specimens, led me to suppose that it was in some way connected with the economy of the polyps themselves, but having discovered its occupant to be one of the coral perforating Sipunculide, which abound in the South Seas, the riddle was quickly solved. The body of one of these parasites, taken from a Bellona Reef specimen, is about of an inch in length, terete, but gradually increasing in diameter from before backwards, and exhibiting a permanent curvature forwards, corresponding with that of the bur

row.

The crested proboscis is about three times the length of the body, and crowned with simple ciliated tentacula. On the dorsal surface, immediately behind the base of the proboscis, is a little oval and brownish callosity, answering the purpose of an operculum, when the animal is retracted into its cell, and close behind this disk is the anal aperture. The posterior extremity of the body is furnished with a similarly constituted, but slightly conical, shield. As the opercular disk meets the rest of the dorsal surface, at an angle more or less obtuse, the proboscis appears to hold a subterminal ventral position, and protrudes itself somewhat perpendicularly to the axis of the body. The surface of the latter is beset with minute asperities, disposed serially, or irregularly scattered. These become larger and more numerous towards the dorsal region, and more definitely aggregated at the extremities; they constitute the before mentioned opercular and caudal disks. As they extend themselves on the proboscis they grow smaller, and begin to assume a more orderly arrangement, and finally form into closely set rings of minute and recurved hooks, reaching to the base of the oral tentacula. This parasite is evidently closely allied to the little animal from the Indian seas, named Lithodermis cuneus, by Cuvier, and which was the only species known to him.

In the Coral borers, which are nearly identical with the little animals here noticed, I found that the œsophagus was encircled by a nervous collar, with a cephalic enlargement on either side, from which tentacular nerves arose, and, in contact with which, dark eye specks were distinctly visible; there is also a single ventral nervous chord, giving off lateral nerves at stated intervals, but without any very apparent ganglionic dilatations. I observed, moreover, that the cavity of

the body was lined with a ciliated membrane, which was reflected round the larger branches of a transparent (probably water) vascular system running along the spirally coiled intestine, with its singularly constructed central suspensory ligament. All this militates against the supposed Echinoderm nature of Sipunculus, and give it radiating affinities with the Annelida, Polyzoa and Tunicata, though perhaps only of a representative kind. The simple anatomy of the larval form, the Atlas of Peron, if it be not indeed a permanent one, is also of great importance in this connexion.

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1. Sipunculus Heterocyathi, (natural size) a. Opercular disk. b. caudal disk. 2. Ventral view enlarged. a. Opercular disk. b. caudal disk. c. proboscis. 3. Dorsal view enlarged. a. Opercular disk. b. anus. c. proboscis.

4. Corallum, seen from above, enlarged. a. Columella. b. primary. c. secondary and d. tertiary rays. e. primary. f. secondary and g. tertiary loculi. h.h.h. Openings communicating with the burrow.

5. Lateral view, shewing a. the aperture of the burrow.

[The case of parasitism here described has an especial interest if viewed in relation to the apparently anomalous characters of the paleozoic Pleurodictyon, which we are much inclined to regard as a coral perforated in a similar manner.-EDS.]

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IX.-ON THE MYOLOGY OF THE ORANG UTANG. By William Selby Church, B.A., Lee's Reader in Anatomy, Christ Church, Oxford.

(Continued from Nat. Hist. Rev. for 1861, page 516.)

THE Flexor Longus Pollicis appeared at first sight to be a portion of the Flexor Profundus, but its origin was distinct, as it arose from the radius, and remained distinct from the Flexor Profundus throughout its whole course. It went to the index only in the Orang; and, as it passed through the annular ligament, it sent off a slip to the tendon of the Flexor Profundus. The tendon of this muscle was supplied with a Lumbricalis muscle, inserted as in man; each of the branches of the Flexor Profundus were also supplied with a good-sized Lumbricalis muscle. In the Gorilla, the Flexor Longus Pollicis sends a small tendon to the thumb, though the mass of the muscle has there become a flexor of the index. (Duvernoy, 1. c. p. 106.) In the Magot and Cebus, these muscles become fused on the palm of the hand, forming as it were a common Flexor Profundus. In the Magot, the radial portion, or Flexor Pollicis, went chiefly to the index, and a slip from the ulnar portion, or Flexor Profundus, supplied the chief portion of the tendon going to the pollex. In the Cebus, the same fusion of the muscles took place; but the radial portion was much the stronger, and supplied the thumb with a tolerably strong tendon, as well as the index and middle fingers, the ulnar portion supplying the third, fourth and fifth digits with tendons.

The arrangements of the Lumbricales in these Monkeys was peculiar. They formed a fleshy mass on the palmar surface of the fused tendons; the first and second arose together from the tendon of the index, and partly from that of the third digit and the slip supplying the thumb; the third and fourth arose together from the tendons of the third and fourth digits. They were all inserted on the radial side of the first phalanx of the fingers.

Vesalius states that the Flexor Longus Pollicis is present in the tailless apes, but that it is only a branch from the Flexor Profundus in the tailed ones.

The Flexor Sublimis is subject to many slight variations in man, but in these Monkeys it presented almost the same appearance that it normally does. The Flexor Profundus frequently has a distinct head coming from the internal condyle of the humerus, and fusing with the rest of the muscle lower down. (Theile.t) The Flexor Longus Pollicis has been noticed double; one part going to the thumb as usual, the other joining that tendon of the Flexor Profundus, which supplies the index. (Theile.) And a more frequent anomaly is the presence of a second head from the internal condyle of the humerus, or the receipt of fibres from the Flexor Profundus or the Sublimis, which would appear to parallel the fusion of the Flexor Pollicis and Profundus met with in the bulk of the Quadrumana.

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Mr.

Ditto, p. 249.

McWhinnie mentions, on the authority of Gantzer, a fascicle going from the Flexor Pollicis to the tendon of the index. It is remarkable also that the Palmaris Longus, which is so frequently absent in man, should be present in most of the Quadrumana.†

The Abductor Longus Pollicis or Extensor Ossis Metacarpi was present, as also the Extensor Secundi Internodii Pollicis, but the Extensor Primi internodii was absent. The tendon of the Extensor Ossis Metacarpi Pollicis was split into two portions, the larger being inserted into the os trapezium, and the smaller into the metacarpal bone. In man a small slip of the tendon normally goes to the os trapezium. As no portion of the tendon went to the first phalanx, I see no reason for considering the anterior portion of the tendon as the homologue of the Ext. Primi Internodii, as is stated by Vrolik in the article "Quadrumana," in the Cyclopædia of Anatomy and Physiology. Exactly the same arrangement was found in the Čebus; but in the Magot, the anterior portion was the larger, and the smaller portion was inserted into a sesamoid bone, and not into the trapezium. Both muscles exist in the Chimpanzee (Vrolik, p. 20), and in the Gorilla (Duv. p. 97).

The Extensor secundi internodii was very weak: it arose from the ulna and the interosseous ligament in front of the Extensor indicis. Duvernoy mentions finding it proportionately as large in the Chimpanzee as in man, and as being smaller and weaker in the Gorilla.

The Abductor Pollicis Brevis consisted of three distinct thin muscular layers, which were inserted together into the base of the first phalanx. The innermost layer arose from the os trapezium, the other two from the annular ligament.

The Opponens Pollicis and Flexor Brevis Pollicis presented no points of interest; the Opponens was very weak and small, the Flexor of tolerable size. The Adductor Pollicis was very large, arose from the palmar ligament, which was prolonged down the whole length of the metacarpal bones of the third and fourth digits, and was inserted into the under side of the first phalanx of the thumb. The Adductor was with difficulty divisible into two portions, one coming from the palmar ligament, the other from its metacarpal prolongations; the division between the two was not nearly so evident as in the adductor of the hallux. In the Magot the Adductor possessed two distinct heads, the longer of which came from the external palmar fascia, the shorter from the os trapezium. The Opponens was relatively stronger than in the Orang. The Abductor was formed on the same plan. In both the Cebus and Magot I found a thin

* Mr. McWhinnie, Varieties of the Muscular System. London Medical Gazette, January 1846.

Henle, 1. c., p. 196, mentions the following important variety of the muscle in man, "Instead of the Flexor pollicis longus, the indicator portion of the Flexor digitorum profundus receives a slender head from the common origin of the superficial muscles."-[EDS.]

Ellis, Demonstration of Anatomy, p. 33, 5th edition.

muscular layer, arising from the palmar ligament which formed three small muscular digitations, which were inserted into the radial side of the first phalanx of the fourth and fifth digits, and the third into the ulnar side of the first phalanx of the index. A similar muscular expansion was found in the feet of these monkeys.

The Palmaris Brevis was, I think, absent, but as the animal had been skinned before I examined it, the muscle may have been cut away. Dr. Traill found none in the one he dissected. In the Chimpanzee it is present (Vrolik, 1. c. p. 20). It was remarkably large in the Magot, arching over the whole of the carpal portion of the hand, reaching from the external side of the little finger to the internal side of the thumb; it was present also in the Cebus.

The Abductor, Flexor Brevis and Opponens Minimi Digiti presented no peculiarities worth notice.

The Dorsal Interossei presented the same general appearance as in man, only differing in the greater development of the Abductor Indicis; but the palmar set differed considerably, being seven in number; the index possessed two, the radial one being a broad flattened muscle, which arose from almost the whole length of the metacarpal bone of that finger, and was inserted into the upper and inner side of the metacarpal of the pollex; the one on the ulnar side arose from the under and inner surface of the metacarpal of the index, and was inserted into the first phalanx of the same finger; the middle and ring fingers had each two and the little finger one, similar muscles. In both the Cebus and Magot the dorsal muscles resembled man's, but the palmar ones closely resembled those of the Carnivora; they were also seven in number, and arose from the palmar ligament, as well as from the metacarpal bones, which they completely hid from view.

The hand of the Orang and of the Chimpanzee appears at first sight to be less perfectly organized than that of some of the other Quadrumana, owing to the total absence of any long flexor of the thumb; the absence of this muscle permits of a greater independence of motion in their thumbs than in any of the other monkeys, in which the long flexor exists as a portion of the Profundus. In the Orang and Chimpanzee the great development of the Abductor, and the well marked Flexor Brevis in some degree make up for the absence of the long flexor. The double adductor has been observed in man (M'Whinnie).

This

Wagner, when speaking of the hand of the Quadrumana, says: "The individual mobility of the fingers is much more limited than in man, and this is more particularly the case with the thumb."* is perfectly true of lower Quadrumana, as is shown in the case of the Cebus, but I think in the Baboons and Magots the greater development of the muscles of the thumbt proves that they can move the

* Elements of the Comparative Anatomy of Vertebrate Animals. R. Wagner, p. 18. Translated by Tulk.

This appears to correspond with the Musculus interosseus volaris primus—(a fourth palmar interosseus) described by Henle, 1. c., p. 228, as constant in the human hand.-[EDs.]

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