206 



" THETIS " SCIENTIFIC RESULTS. 



prominent and project considerably beyond the second epimeral 

 denticle and give each lateral margin a tridentate outline. 



There is a spine on the epistome, and a triangular denticle 

 between it and the inferior base of the rostrum. The second, 

 third, fourth and fifth segments have a central longitudinal ridge 

 on the inferior surface ; the first three have a spiniform process 

 anteriorly ; the ridges are absent on the sixth and seventh 

 segments. 



An ill-defined central, compressed denticle is present on the 

 under surface of five of the pleon segments, and there is also a 

 pair of prominent, submedian, truncated processes to which the 

 pleopoda are articulated. Segments and epimeral processes of 

 the pleon subequal, sides obtuse, with the anterior margin oblique 

 and the posterior nearly straight Terminal segment truncated, 

 as long as the three preceding combined. Upper aspect with a 

 submedian pair of short spines posteriorly and a strong, short, 

 median ridge on the anterior half of its sui^face. Sides sloping, 

 becoming wider to the insertion of the uropods, beyond which the 

 margins are keel-like and minutely denticulate. 



The upper antennae have the basal joint tapering, triangular, 

 and about three times as long as broad, the angles are rather 



strongly denticulated and the 

 superior surface carries a low 

 smooth longitudinal ridge ; 

 the lower distal extremity 

 bears a small spinule. The 

 second joint is wider above 

 than below and is a little 

 longer and much stouter than 

 the third. The larger flagel- 

 lum consists of eight articula- 

 tions; the first three are 

 equal; the succeeding joints 

 are about one-third longer 

 and of nearly equal length ; 

 all except the first pair bear 

 two or more sette at their 

 extremities. Smaller flagel- 

 lum with four articulations, 

 the first two of which are 

 equal ; the third is much 

 the longest ; distally each 

 joint carries two or three 



Ul'PKR A.STENNA. Sptlt 



Fig. I5b. 

 Lower antennae having the peduncle shorter than tlie basal 

 joint of the upper ; first joint short, broad, with a denticulated 



