BENTHESICYMUS TANNERI. 205 



Benthesicymus tanneri Fax. 

 Plate H. 



BuU. Mus. Comp. ZooL, XXIV. 215, 1S93. 



Integument .smooth, membranaceous. Eostrum short, acute, laterally 

 compressed, raised above the orbit into a cre.st which is armed with two 

 slender acute teeth ; the lower margin of the orbit is fringed 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-hepatic groove 

 is pronounced, and is followed by another obsolescent, transverse, cervical 

 furrow farther 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 pterj'gostomian area by an oblique 

 suture. A sliglit 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 carinate 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 loug 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 setae. The terminal segment of the endopod of the third 

 maxilliped is flattened, truncate, and armed with about four strong spines on 



