122 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



and sparsely ciliate below ; upper surface near the inner margin and. 

 both fingers thickly ciliate; inner border of hand short, serrate, the 

 serrations hidden by the cilia; outer margin of hand ribbed; movable 

 finger serrate and ciliate on outer margin; both fingers ribbed on upper 

 surface and bearded at base on inner margins, the beard being most 

 dense on the outer finger. Carpus triangular, lightly grooved above, 

 ciliate along the distal margin; a small spine at the superior internal 

 angle and behind it a few very minute denticles, inner surface heavily 

 bearded along the distal margin ; median spine large and curved strongly 

 forward; distal border beneath ciliate, and with three well-developed, 

 acute spines. Distal margin of meros bearded above and within, two 

 small spines above at the distal end ; beneath, of the usual two rows of 

 spines, the outer row is represented by two or three strong spines, the 

 inner by a row of small teeth ; between the rows there is, in some speci- 

 mens, a ciliated patch. Third pair of legs hooked. First pair of 

 abdominal appendages of medium length, reaching forward to the 

 middle of the basal segments of the second pair of legs, very slender 

 and bifid for only a short distance from the tip; inner branch con- 

 siderably shorter than the outer, the tip acute and turned slightly 

 backward and outward across the outer branch, the tip of which is com- 

 pressed and recurved. 



Female. — Not known. 



Seven specimens, the largest nearly 2 inches in length. 



In some respects this species resembles quite closely Gambarus na'is 

 Faxon, from the same region. I have not been able to compare Dr. 

 Faxon's types with the species here described, but as his description 

 makes no mention of the heavily ciliate chelipeds, a character which 

 could not have escaped his observation, and fails to agree in other 

 respects, I feel no hesitation in considering the specimens from Beloit 

 representatives of a new species. 



CAMBARUS CLYPEATUS. 



Type locality.— Jia^y St. Louis, Mississippi; U. S. Biological Survey, 

 collector, 1892. 



Type.—^o. 22778, U.S.N.M. 



Male, form I, not known. 



Male, form II, not known. 



Female. — Eostrum long, very broad, flat, hardly at all excavated, 

 sides slightly raised, sharp, diverging slightly from the base to about 

 the middle, then converging to near the tip where they abruptly tarn 

 in to the middle line; the tip of the rostrum is round, and the usual 

 lateral teeth are not represented, even by angles. Postorbital ridges 

 short, grooved on outer face, anterior spines wanting. Carapace 

 smooth and polished above, lightly punctate on the sides, anterior 

 margin hardly angulated; cervical groove sinuate, broken on the sides; 

 lateral spine wanting; branchiostegian spine minute; areola wide. 



