BENTHESICYMUS TANNERI. 205 
Benthesicymus tanneri Fax. 
Plate H. 
Bull. Mus. Comp. Zool. XXIV. 215, 1893. 
Integument smooth, membranaceous. Rostrum short, acute, laterally 
compressed, raised above the orbit into a crest which is armed with two 
slender acute teeth; the lower margin of the orbit is frmged with long 
closely set hairs. The rostral crest is continued backward as a sharp keel 
on the median line of the carapace, as far as the cervical groove ; posterior 
to this the carina is obsolescent. The lower angle of the orbit is prominent, 
but not spiniform, the branchiostegal spine is prominent, the pterygostomian 
angle sharp but unarmed. The dorsal portion of the gastro-hepatie groove 
is pronounced, and is followed by another obsolescent, transverse, cervical 
furrow further back on the carapace, —a furrow which forms the anterior 
boundary of the cardiac area. The branchial area is bounded above by a 
blunt ridge and is separated from the pterygostomian area by an oblique 
suture. A slight carina runs from the branchiostegal spine to the branchio- 
pterygostomian suture. The infero-lateral margin of the carapace is nearly 
straight. 
The first three segments of the abdomen are thick, rounded, and devoid 
of dorsal carina or tooth; the fourth segment is faintly carinate but not 
toothed ; the fifth and sixth are distinctly carimate and armed with a small 
acute posterior tooth. The telson is short, convex above, and armed with 
three pairs of minute lateral spines. 
The eye-stalks are about as long as the rostrum and have the form 
characteristic of the genus; the eyes are of a dark brown color. The basal 
segment of the antennule is armed externally with a stylocerite which is 
much shorter than the segment, and with a small acute spine at the distal 
external angle. The antennular flagella are nearly as long as the body. 
The second segment of the antenna is devoid of an external spine; the 
scale is broad, foliaceous, narrowed at the distal end; the flagellum is slen- 
der and much longer than the body. The merus of the second maxilliped is 
long and narrow, its inferior distal angle not produced beyond the base of 
the carpus; the exopod is much longer than the endopod, reaching forward 
to the distal end of the antennal peduncle; it is fringed on both sides with 
very long, delicate seta. The terminal segment of the endopod of the third 
maxilliped is flattened, truncate, and armed with about four strong spines on 
