RHINOCARIDv®. 
RHINO CAR IS, N. G. (J. M. C.). 
Rhinocaris coltjmbina, n. sp. 
PLATE XXXI, FIGS. 16-21. 
Cephalothorax elongate-siliquiform. Surface normally arched or sub-cylin¬ 
drical, and probably somewhat flattened toward the ventral margin. The 
anterior extremity is slightly depressed on the dorsum and produced into a 
prora or rostrum, which is vertically flattened and gently deflected toward the 
tip. On each side toward its base this prora bears a low ridge which is con¬ 
tinued on the body of the carapace, accompanied by a faint ridge, which 
lies in the axial line. These ridges appear to extend the entire length of the 
carapace, though indistinctly seen on most examples on account of the lateral 
compression which has usually fractured the carapace irregularly along the 
dorsum. Below the prora the margin curves rapidly downward to the ventral 
edge, where it is nearly straight for a short distance, thence curving upward 
to the posterior margin, which is transverse and incurved over the axial 
line, the posterior extremity being thus truncate. The optic spot appears to 
be indicated by a faint tubercle in the cephalic region, close to the axial 
line. There is no evidence of a nuchal furrow, and the limits of the cephalic 
and thoracic areas are thus indistinguishable. 
Surface free of nodes or tubercles, but ornamented with faint pits on the 
dorsal region and on the lateral areas with fine, raised, anastomosing lines, 
which are sub-parallel to the margin, and converge toward the anterior and 
posterior extremities. In all the specimens thus far obtained the carapace 
