ORTMANN: THE CRAWFISHES OF THE STATE OF PENNSYLVANIA 359 



Bochi not very rol)nst, not pubescent, with only a few, scattered, short hairs, 

 chiefly on the chehe, but the hair wears off very soon, and the body becomes smooth, 

 with exception of a sh'ght pubescence at the base of the cutting edges of the fingers. 



Carapace subovate, depressed. ReUition G: H: B — \ A -.1.2 or 1..3. (The widtli 

 of the branchial regions appears slightly less than in G. liviosus, but tins is probably 

 due to the fact that the specimens of C. lywpinquus at hand are rather small). 

 Greatest width of brancihial regions well behind, at al)out the middle of the bran- 

 chial regions. Carapace flattened dorsally. 



Geroical groove deep, more or less distinctly interrupted on the sides just above 

 the lateral spine. Posterior .section of carapace about half as long as anterior (rela- 

 tion a :^j = 1:0.42 to 0.62. 



Areola rather broad, tu:l = 1:4.7 to 6.0, with about four irregular rows of 

 punctures. 



Ro)<tnnu long and broad, reaching to the middle of the fifth joint of the peduncle 

 of the antenna^and to the end of the peduncle of the antennula, sometimes slightly 

 shorter. Surface concave, with a more or less distinct, low. longitudinal median 

 keel toward tlie tip. Margins elevated, but not much thickened, straight, more or 

 less convergent toward the marginal spines. Marginal spines generally well devel- 

 oped in young specimens, less so in older ones, sometimes quite small. Acumen 

 long, triangular, comparatively longer in young specimens, pointed, about one-third 

 as long as the whole rostrum, or shorter. Postorbital ridges slightly divergent pos- 

 teriorly, ending anteriorly in a moi-e or less distinct small spine. 



Surface of carapace finely j)unctate, and slightly granulate on the hepatic regions 

 in old specimens. Sides witli only one spine on the branchial regions, immediately 

 be]iin<l the cervical groove. This spine is always present and sharp, but generally not 

 very large. No other spines on the sides of the carapace. External orbital angle not 

 marked. Branchiostegal spine small, but sharp, or tuberculiform, or even obsolete. 



Abdomen longer than carapace, slightly narrower than the carapace in the male, 

 about as wide as the latter in the female. Anterior section of telson on the outer 

 posterior corners with one to three spines (two spines is the general condition). 

 Posterior section of telson semielliptical, considerably wider than long, and slightly 

 shorter than anterior .section. 



Kpisto'ina with posterior part short and broad, almost three times as wide as long, 

 not plane, with a ti'ansverse groove and an anterior median depression running into 

 each other. .Vntt'rior section constricted at base, its anterior margin generally almost 

 semicircular, witli a median point and an indistinct angle on i-aeh side, but shape 

 rather vavial)U': sometimes it is truncate anteriorlv, with or without median point. 



