CAMBARUS. 105 



of tlie outer row are developed. Third pair of legs hooked at base. First 

 pair of abdominal appendages long, deeply bifid, rami slender, recurved, 

 parallel, inner ramus spoon-shaped at tip, outer ramus a little longer than 

 the inner, compressed laterally, tapering to a fine point at tip. 



Male, form II. — Lateral rostral spines a little more prominent, hand 

 smaller, hooks on third legs less strongly developed, first abdominal ap- 

 pendages thicker, bifid for only a short distance from the ti]}, rami laterally 

 compressed, blunt-pointed. 



Female — Rostrum as in the second form of the male, hand shorter and 

 Avider. Annulus ventralis with well-marked transverse fossa. 



Measurements of a male, form I. — Length, 55 mm. Carapace, 25 mm. 

 Abdomen, 30 mm. Length of antennae, 50 mm. Length of areola, 7 mm. 

 Breadth of areola, 2.5 mm. Length of chela, 21 mm. Breadth of chela, 

 9 mm. Length of movable finger, 12.5 mm. 



A female of the same size has the areola 3 mm. in width, 7 mm. in 

 length. 



Forty specimens, including both forms of the male and the female, were 

 collected by C. L. Herrick in Second Creek, Waterloo, Lauderdale Co., Ala., 

 for the U. S. National Museum. Tlie male appendages are very like those 

 of C. 3Imtss{pj)ieiisis, the rami being longer and less strongly recurved than 

 in C. iwmunis. It is at once distinguished by its broad and short areola from 

 the other species in which the first abdominal appendages are formed after 

 the pattern of those of C. immiinis. The section of the carapace behind the 

 cervical groove is very short in this species, and the dense beard at base of 

 the external finger is very characteristic. In C covij)resstis the areola, al- 

 though broad, is long, and the strong lateral compression of the body, differ- 

 ent form of the chela, etc., distinguish it from this species at a glance. 



45. Cambarus compressus. 



Plate V, fig. 6. Plate X. figs. 8, 2', 3 a, 2 a'. 



Cfimbariis cfimprcsxns, F.wnx, Proc. Amor. Acad. Arts aud Sci., XX. 127, 1884. 



Male, form I. — Rostrum narrow, excavated, curved downwards, with a 

 longitudinal median carina ; margins thickened, converging, with a line of 

 ciliated dots; acumen long, triangular, with acute lateral spines at base 

 which are obsolescent in the largest specimens. Cephalothorax strongly 

 compressed laterally. Post-orbital ridges armed with acute anterior spines. 



14 



