6 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
are really a distinct but closely allied and much larger species. Very 
small specimens, 10”™ or less in length of carapax, resemble the depressus 
very much, but are distinguished from Milne-Edwards’s figures and the 
type specimen referred to by the less regularly triangular outline of the 
carapax, the hepatic and branchial regions being much more protuber- 
ant; by the acute rostral horns, more widely separated at their tips; by 
the much longer interantennular spine, which is fully as long as in Eu- 
prognatha rastellifera ; by the short and conical or even tubereuliform 
gastric and cardiac spines; by the spine of the first somite of the abdo- 
men being directed backward instead of upward; and by the more slender 
chele. 
Male.—In large males over 20™™ in length of carapax, the carapax 
is a little over three-fourths as broad as long, and thickly covered, as 
well as nearly all otber parts of the animal except the chelz, with 
strongly curved hairs or sete, which, in every specimen seen, persist- 
antly retain a thick coating of soft mud. Therostral horns are slender 
and separated by a rounded sinus, at the bottom of which the inter- 
antennular spine, or true rostrum, which is much longer than the rostral 
horns and grooved longitudinally in front, projects downward and about 
as far forward as the rostral horns. The basal segment of the antenna is 
armed with a lateral and an inferior ridge, each divided into three to five 
short spiniform teeth. The postorbital processes are broad, but acutely 
triangular, and project as far as the tips of the eyes. The dorsal sur- 
face is thickly covered with granular tubercles, and there is a slight 
tubercular elevation, but little more prominent than the tubercles of 
the general surface, on the gastric region, and another on the cardiac, 
in place of the spines in the young. The hepatic region is divided 
obliquely near the middle by a deep suleus into two lobes, of which the 
superior projects in a rounded prominence, which is very conspicuous 
as seen from above, while the inferior is crossed longitudinally by the 
pleurotergal suture and below it armed with a short series of small tuber- 
culiform spines. The branchial regions are prominent, swollen, and 
evenly tuberculated. 
The chelipeds are stout and approximately once and a half as long 
as the carapax; the merus is triquetral with the angles armed more or 
less with tubercles or tuberculiform spines; the whole outer surface of 
the carpus is similarly armed. The chela is approximately two-thirds 
as long as the carapax, naked, smooth, polished, and unarmed, except a 
very few tubercles on the inner surface and near the proximal ends of 
the upper and under edges; the body is nearly as long as the digits, 
thick and swollen; and the digits are compressed, somewhat grooved 
longitudinally, very slightly curved, gaping at the bases, and with the 
prehensile edges slightly and irregularly crenate. The ambulatory legs 
are hairy to very near the tips, but are otherwise unarmed and smooth 
throughout, and all the segments are subcylindrical ; the first are about 
two and a half times as long as the carapax, the others successively 
