150 STALK-EYED CRUSTACEA. 
curves upward, defining the upper limit of the branchial region, and is 
finally lost just before reaching the hind margin of the carapace. The 
anterior part of this carina is separated from the orbital spine and the he- 
patic area by a deep groove ; below this carina there is a deep vertical inden- 
tation on the side of the carapace between the hepatic and branchial areas, as 
in all the species of this genus in which the middle lateral carina is obsolete. 
The inferior lateral carina extends from the branchiostegal spine, with 
which it is continuous, backward, pursuing a more nearly horizontal course 
than the upper one, and stops before reaching the hind border of the 
carapace. 
The third abdominal segment is keeled along the median dorsal line. Its 
hinder half is sharply bent down at angle of about 90°, forming a prominent 
knee. There are no median teeth on this or any of the other abdominal 
segments. The end of the telson is acutely triangular, and is armed with 
three pairs of articulated spines; the intermediate pair of these spines are 
much the stoutest and longest. The dorsal face of the telson is armed with 
four pairs of spines articulated at their bases. 
The two flagella of the antennule are subequal, and about as long as the 
whole body minus the rostrum. The basal segment of the antennule is 
armed externally with a spine whose acute tip reaches forward to the middle 
of the second segment of the peduncle. The antenna with its flagellum is 
about twice as long as the body (rostrum included); the scale is one half the 
length of the rostrum, its sides convex, its external spine subterminal. 
The right carpus of the second pair of legs is composed of nine or ten 
segments, the left of twenty-two to twenty-four. The merus of the left 
leg of the second pair is also obscurely divided up into many (nine or ten) 
secondary segments or annuli, as in other species of this genus. 
The last pair of abdominal appendages are about as long as the telson, 
the outer branch being slightly longer than the inner. 
Length, 110 mm.; rostrum, 26 mm.; carapace with rostrum, 55 mm. ; 
antenna, 219 mm.; antennal scale, 14 mm.; telson, 17 mm. 
This species was taken at four stations in the Gulf of Panama, viz: — 
Station 3385. 286 fathoms. 49 specimens (“a peck rejected”’). 
eo 8386, 4242-0 4< 91 cs 
eR oooU ae LO 7 “ 
Sal asd396. 25910566 18+ 50 juv. 
Heterocarpus vicarius is closely related to H. gibbosus Bate, described from 
