CAMBARUS. 119 



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 chelipedsj 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. 



Knotvn Localities. — Kentucky : Grayson Springs, Grayson Co. ; Green 

 River, near Mammoth Cave ; Cumberland Gap. 



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

 Faxon, and 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. affiiiis 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. 



50. Cambarus forceps. 



Plate V. Hg. 4, Plate IX. flgs. 5, 5', 6 a, S a'. 



Camharus forceps, Faxon, Proc. Amer. Acad. Arts and Sci., XX. 133, 1884. 



Male, form I. — Eostrum narrow, excavated, faintly carinated in the mid- 

 dle ; margins divergent at the base, thickened, dotted-lined ; acumen long 



