112 A REVISION OF THE ASTACIDA. 
The types of C. suvenils 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 far 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 fer, 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. rusticus the sides of the areola, after 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 short, 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. rusticus. 
Two female specimens from Cumberland Gap, Ky. (M. C. Z., No. 5580) 
agree with the types of CO. guventis from Little Hickman, 
Hagen’s type of C. juvenilis 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. 8446) 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 OL juveniis and C. rusticus be separated as two distinct species, it is hard 
to say to which 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 chelipeds. The internal median 
