Between the ridge and the sternal plates of the fourth pair

of legs there is a deep transverse fossa.

Measurements of a male, form I.: Length of body, 60 mm. Length of carapace, 30 mm. Length of abdomen, 30 mm. From end of rostrum to cervical suture, 20 mm. From cervical suture to posterior border of carapace, 10 mm. Breadth of rostrum at base, 4 mm.

Length of rostrum, 10 mm. Length of rostral acumen, 3 mm.

Width of areola, 1.5 mm. Length of antennæ, 60 mm. Length of chela, 25 mm. Breadth of chela, 12 mm. Length of movable finger, Internal border of hand, 7 mm.

17 mm.

In one specimen, a male, form I., the fingers are very much elongated, not gaping at base. The length of the internal border of the hand in this specimen is 7.5 mm.; the length of the movable finger, 21 mm.

Irondale, Mo. Collected by E. Harrison.

This species resembles C. rusticus in its general form. The male appendages, as well as the annulus ventralis of the female, however, are very different from those of any previously described species. The male appendages approach in form those of C. propinquus more nearly than any other, but in that species these appendages are more deeply bifid, and not recurved.

The second form of the male is unknown.

Male, form I. Rostrum broad, sub-excavated, margins nearly parallel, with a line of ciliated puncta; acumen long, equal in length to the width of base of rostrum, narrow, acute, with a black, horny tip and lateral spines. Post-orbital ridges sulcate on external side, inflated at posterior end, armed with a sharp, horny-tipped auterior spine. Carapace long-oval, slightly flattened above, heavily punctated, sides rough with ciliated granules; cervical groove deep, lightly sinuate, broken on the sides just above the small, acute lateral spine; branchiostegian spine slightly developed; anterior lateral margins angulated, but without sub-orbital spine. Posterior segment of carapace equal in length to one half the distance from tip of rostrum to cervical groove. Areola of moderate width, punctated. Abdomen as long as cephalo-thorax, pleuræ punctate, telson bispinose on each side. Anterior process of epistoma ciliated, triangular, sides convex, marginated. Basal segment of antennule armed below with an internal ante-apical spine. Antennæ slender, about as long as the body, scale as long as the rostrum, of moderate width, external border inflated,

ending in a sharp spine. Third maxillipeds hairy within and below. Chelipeds stout; chela large, external margin convex; hand ciliatopunctate above and below (the dots large), swollen above, internal border of moderate length and furnished with two or three rows of depressed ciliate tubercles; fingers gaping at base, at least in large individuals, costate and punctate-lined, external margin of movable finger with depressed ciliated tubercles irregularly disposed in two rows; tips of fingers incurved, horny. Carpus smooth or faintly tuberculate above, a large, acute median internal spine, and small proximal and distal internal spines; beneath, the carpus has a very minute or no median anterior spine, a short and acute external spine. Meros with two superior, obliquely placed ante-apical spines; of the ordinary biserial inferior spines only the distal one or two of the outer row are developed. Third pair of legs hooked on third segment. Thoracic sterna hairy. First pair of abdominal appendages very long, reaching the base of the chelipeds when the abdomen is flexed, tuberculated on internal border at the base, deeply bifid, rami slender, acute, forming an acute angle with the basal part, the outer slightly recurved, the inner shorter, incurved, and a little dilated before the tip; a projecting angle or shoulder on the anterior border at base of rami.

Male, form II. Chela smaller, fingers not gaping, hook on third segment of third pair of legs smaller; first pair of abdominal appendages split only half as far down as in the first form, rami much thicker, no projecting angle on the anterior border; these appendages are as long as in the first form, reaching forward to the base of the chelipeds; they are articulated near the base.

Female. Chela shorter and wider, external finger bearded within at base; sternum between fourth pair of legs non-tuberculate, lightly ciliate. Annulus ventralis large, transverse fossa broad and deep, anterior border bituberculate.

Measurements of a male, form I.:-Length of body, 73 mm. Length of carapace, 36 mm. From tip of rostrum to cervical groove, 24 mm. From cervical groove to hind border of carapace, 12 mm. Length of rostrum, 11 mm. Breadth of rostrum at base, 4.5 mm. Length of acumen of rostrum, 4 mm. Width of areola, 2.5 mm. Length of abdomen, 37 mm. Length of chela, 34 mm. Breadth of chela, 14 mm. Length of movable finger, 22 mm.

Known localities. Kentucky: Grayson Springs, Grayson Co.; Green River, near Mammoth Cave; Cumberland Gap.

M. C. Z., Cat. No. 3574 (young female), from Knoxville, Tenn.,

Walter Faxon, and Cat. No. 3575 (male, form II.), from Bradford, Ind., A. S. Packard, Jr., probably belong to this species, but the specimens are too young to determine with confidence.

This species resembles C. spinosus, from which it is easily distinguished by the length of the posterior section of the carapace, and by the length of the male appendages. From C. affinis it may be separated by the different form of the male appendages and female annulus ventralis, and by the single lateral spine of the carapace. I have seen males of the first form only 34 mm. in length.

20. C. FORCEPS, sp. nov.

Male, form I. Rostrum narrow, excavated, faintly carinated in the middle; margins divergent at the base, thickened, dotted-lined; acumen long and narrow, horny tipped; lateral spines small. Post-orbital ridges not very prominent except anteriorly, where they terminate in a spine with a corneous tip. Carapace cylindroidal, punctate above, granulated on the sides, antero-lateral margins bluntly angulated; cervical groove sinuate; small and acute lateral spine: no branchiostegian spine; areola of moderate width, punctate. Abdomen as long as the cephalo-thorax: telson rounded behind, bispinose on each side. Epistoma smooth, anterior process triangular, in some specimens truncate. Thoracic sterna with silky setæ at bases of the legs. Antennæ slender, as long as the body; scale a little longer than the rostrum, of moderate width, sub-truncate at distal end, outer margin ending in a long, sharp, somewhat outwardly directed spine. Third pair of maxillipeds hairy within. Chelipeds short, stout; chelæ large, wide, with slender cylindrical, widely-gaping fingers, which are curved outward at the base and opposable only at their tips; hand thickly punctated above and below, inner margin obscurely serrate; fingers naked at base, with parallel rows of ciliated dots; a dark band around both the inner and outer fingers a little distance from the tip. Carpus punctate above, a strong, sharp internal median spine; below there is no anterior median spine, and only a very minute external one. Meros short; of the biserial inferior spines only the distal one in each row is usually developed to any extent; above there are commonly two obliquely placed ante-apical spines, in some specimens only one. Distal portion of the following pairs of legs furnished with long setæ, especially long on the second pair of legs. Third segment of third pair of legs hooked. First pair of abdominal appendages long, deeply bifid, rami slender, straight, parallel, the outer a little longer than the inner, and a little recurved at the tip. In some specimens the anterior border at the

base of the rami has a projecting angle or shoulder, but in most specimens this is not evident.

Female. Fingers straighter. Base of external finger has a dense beard on the inside; in a few of the specimens seen the fingers are longer, nearly straight, their opposed margins almost meeting throughout their length. Annulus ventralis bilaterally symmetrical, anterior margin bituberculate, posterior margin unituberculate, fossa transverse. Dimensions of a male, form I.:- Length of body, 38 mm. Length of carapace, 19.5 mm. Length of abdomen, 18.5 mm. From tip of rostrum to cervical groove, 14 mm. From cervical groove to posterior border of carapace, 6 mm. Length of rostrum, 5 mm. Length of acumen of rostrum, 2 mm. Width of areola, 1 mm. Length of an

tenna, 36 mm. Length of chela, 16 mm. Length of movable finger, 10.5 mm.

Breadth of chela, 7.5 mm.

The largest female specimen is 60 millimeters in length.
Cyprus Creek, Lauderdale Co., Ala.

Nine specimens, four males of the first form and five females, collected by C. L. Herrick for the U. S. National Museum, October, 1882. This is a small species with large hand, slender fingers widely separated at base and meeting only at the tips. In the female, there is a heavy beard at base of external finger on the inner side.

In the summer of 1872 I collected in a brook at Knoxville, Tenn., six specimens, three second form males and three females, which closely resemble those obtained by Mr. Herrick in Alabama, and belong, I think, to the same species. The external finger of the males is densely bearded within at the base, as in the females from Lauderdale Co., Ala., the first abdominal appendages reach forward to the base of the second pair of legs, are bifid at the tip, the internal and external parts are thick, blunt at the tip, the outer somewhat longer than the inner, and slightly recurved at the tip.

§ 5. Second and third pairs of legs of male hooked.

21. C. SHUFELDTII, sp. nov.

Male, form I. Rostrum plane above, margins a little convergent, raised into a slight rim from the base to the lateral spines, which are prominent and acute; acumen of moderate length, acute, pubescent. Post-orbital ridges with anterior spines. Carapace smooth, a sharp spine on the cervical groove on each side; sub-orbital angle prominent, branchiostegian spine present. Areola of moderate breadth. Telson bispinous on each side. Epistoma triangular. Antennal scale broad.

Hand smooth, cylindrical, inflated; fingers slender, incurved at the tips. Carpus smooth, armed with a single spine on the antero-inferior border. Meros provided with a single spine near the distal end of the superior margin and two or three below. Third segment of second and third pairs of legs hooked. First pair of abdominal appendages straight, bifid, inner part ending in a straight, acute tip, outer part split at the tip into two straight acute points.

In the second form of the male the hooks upon the thoracic legs are very slightly developed, and the first abdominal appendages are less deeply cleft, with blunter and less finished tips. The chela is shorter.

In the female the chela is much shorter, broader, and less cylindrical, the abdomen broader. Annulus ventralis a transverse curved ridge, the hind side of the ridge concave.

Length, 19 to 27 mm.

Locality. Near New Orleans, La.

Found with C. Clarkii in the collection made by Dr. R. W. Shufeldt, U. S. A., in 1883, now in the U. S. National Museum.

This is a minute species closely related to C. Montezuma from Mexico. Like that species, it has the second and third pairs of legs hooked in the male, a condition which normally obtains in no other species known.* C. Shufeldtii is distinguished from C. Montezuma by the presence of a lateral spine on the carapace and by the form of the male appendages. In the latter species the tips of these appendages are recurved, the inner part flattened at the end into a spoon-shaped surface. In C. Shufeldtii the tips of these organs are straight, and each of the three points in which they terminate is acute.

LIST OF THE KNOWN SPECIES OF CAMBARUS AND ASTACUS.

1. CAMBARUS BLANDINGII.

Astacus Blandingii, Harlan, Trans. Amer. Philosoph. Soc., III. 464. 1830. Med. and Phys. Res., p. 229, fig. 1. 1835. Astacus (Cambarus) Blandingii, Erichson, Arch. Naturgesch., Jahrg. XII., Bd. I., 98.

1846.

?Astacus Blandingii, Le Conte, Proc. Acad. Nat. Sci. Phila., VII. 400. 1855.

I have seen two or three abnormal specimens of C. virilis and C. propinquus with a like disposition of hooks on the legs.