246 THE COMPARATIVE MORPHOLOGY OF THE CRAYFISH. 
rather more convex than the posterior, in the females. 
The tergal surface of the telson is not divided into two 
parts by a suture (fig. 61, 1). The anterior process of 
the epistoma is of a broad rhomboidal shape, and there 
are no distinct lateral spines. 
The squame of the antenna is not so broad relatively 
to its length; its inner edge is less convex, and its outer 
edge is slightly concave; the outer basal angle is sharp 
but not produced into a spine. The opposed edges of 
the fixed and movable claws of the chele of the forceps 
are almost straight and present no conspicuous tubercles. 
In the males, the forceps are vastly larger than in the 
females, and the two claws of the chele are bowed out, so 
that a wide interval is left when their apices are applied 
together; in the females, the claws are straight and the 
edges fit together, leaving no interval. Boththe upper and 
the under surfaces of the claws are almost smooth. The 
median ridge of the endopodite of the sixth abdominal 
appendage is more marked, and ends close to the margin 
in a small prominent spine. 
In the females, the posterior division of the sternum of 
the penultimate thoracic somite is prominent and deeply 
bilobed; and there are some small differences in form in 
the abdominal appendages of the males. More especially, 
the rolled inner process of the endopodite of the second 
appendage (fig. 62 F, f) is disposed very obliquely, and 
its open mouth is on a level with the base of the jointed 
part of the endopodite (g) instead of reaching almost to 
