112 A REVISION OF THE ASTACID^. 



The types of C.jureniUs from Little Hickman, Ky. (M. C. Z., Nos. 213, 

 3347) differ from the types of C. rusticus in the following respects. The first 

 pair of abdominal appendages are longer, reaching forwards as fixr as the 

 base of the chelipeds when the abdomen is flexed ; the rami are slenderer, 

 longer, and set at a slight angle with the basal part of the appendage ; the 

 inner ramus is straight, parallel with the outer ramus (not twisted), pointed 

 at the tip, not dilated. The margins of the rostrum are more thickened. 

 The punctation of the carapace is liner. The areola is narrower, the nar- 

 rowest part being in front of the centre, thence widening posteriorly ; it fol- 

 lows that the sides of the areola are not parallel for any distance, whereas 

 in C. rnsticm the sides of the areola, alter converging to the posterior end 

 of the anterior triangular field, run nearly parallel to one another for some 

 distance, diverging towards the posterior end of the carapace to form the 

 hinder triangular areolar field. The hand is sliort, with long fingers which 

 meet throughout their entire length ; the external finger is barbate within 

 at base. In the male of the second form the tip of the outer ramus of the 

 first abdominal appendages is slightly recurved. 



There is, however, some variation among these types. In one male of 

 the first form the fingers are of moderate length, slightly gaping at the 

 base, the inner carpal spine small but acute ; the areola is of the form seen 

 in C. ruslicm. 



Two female specimens from Cumberland Gap, Ky. (M. C. Z., No. 3580) 

 agree with the types of C.jurciu'i/s from Little Hickman. 



Hagen's type of C. jiireiiilis from the Osage River (M. C. Z., No. 271) 

 differs from the Kentucky types, and agrees with the specimens from the 

 Osage River (M. C. Z., No. 3446) mentioned farther on. 



Among specimens received from Perryville, Ky. (M. C. Z., Nos. 3442, 

 3443) and Salt River, Ky. (M. C. Z , No. 3578), which agree in most respects 

 with Hagen's types of C. rusticus, many have an inflated hand, with very 

 convex external border and rather short fingers. The carapace is flattened 

 on the back. In many respects these specimens resemble C. juvenilis ; and 

 if 0. juvenilis and C. rusticus be separated as two distinct species, it is hard 

 to say to wliicli species these specimens should be assigned. 



Specimens from Cumberland Gap, Ky., males of the first form (M. C. Z., 

 No. 3444), have the rami of the first pair of abdominal appendages long 

 and .slender, as in C. juvenilis ; when the abdomen is flexed, these appen- 

 dages reach forward to the base of the clielipeds. The internal median 



