CAMBARUS. 105 
of the 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 tip, rami laterally 
compressed, blunt-pointed. 
Female — Rostrum as in the second form of the male, hand shorter and 
wider. Annulus ventralis with well-marked transverse fossa. f 
Measurements of a male, form I.— Length, 55 mm. Carapace, 25 mm. 
Abdomen, 50 mm. Length of antenne, 50 mm. Length of areola, 7 mm. 
Breadth of areola, 2.6 mm. Length of chela, 21mm. Breadth of chela, 
9mm. Length of movable finger, 12.5 mm. 
A female of the same size has the areola 3mm. 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. The male appendages are very like those 
of C. Mississippiensis, the rami being longer and less strongly recurved than 
in C.immuns. 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. smmunis. 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. compressus 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. 2, 2', 2a, 2a'. 
Cambarus compressus, Faxon, Proc. Amer. Acad. Arts and 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 
