NO. 3573 COPEPODS — HUMES AND HO 15 



mentation, i.e., with spinous processes on both sides of 2 spines and 

 with seta naked. Paragnath absent. First and second maxillae 

 and maxilliped like those in H. latipes. 



Area behind mouth and between mouthparts with median lobe 

 (lingua) weakly developed. Postoral area between maxillipeds and 

 leg 1 (fig. 65) less protuberant than in H. latipes. 



Legs 1-4 with same spine and setal formula as in H. latipes, except 

 for endopod of leg 1 being 0:1; 0:1; 1,4. Leg 1 (fig. 68) with inner 

 spine on basis 22^ long and adjacent spiniform process asymmetrically 

 bifm-cated; terminal segment of endopod with 4 setae and with 3 

 small and rather obtuse processes between spine and first seta. 

 Legs 2-4 resembling those of H. latipes. 



Leg 5 (fig. 69) with relatively slender free segment, 61m along inner 

 and ventral margin, 51 /x along outer and dorsal margin, and 22ai 

 wide. Armature from dorsal to ventral consisting of spine 21/i, 

 seta 50m, spine 25/x, and spine 40m in length, all ornamented as in 

 figure. 



Leg 6 probably represented by spine and seta near attachment of 

 each egg sac (see fig. 61). 



In other respects similar to H. latipes. 

 Color in life unknown. 

 Male.' — Unknown. 



Etymology. — The specific name cognatus, from Latin, meaning 

 "related or closely allied," refers to apparent close relationship be- 

 tween this species and H. latipes. 



Comparison with related species.—^, cognatus differs from 

 H. furcifer Sars (1917) in lacking a spine such as described on the 

 first segment of the first antenna in the Norwegian species, in having 

 3 terminal elements instead of 4 on the mandible, in having a 4-seg- 

 mented maxilliped with a terminal fanlike fringe, in having the last 

 segment of the endopod of leg 1 armed as 1,4 instead of 1,11,3 as in 

 Sars' species, and in having a relatively much shorter caudal ramus, 

 3:1 instead of 13:1 as in R furcifer. The length of the female is 

 0.90 mm instead of 1.40 mm as in the species described by Sars. 



H. cognatus apparently is closely related to H. latipes but differs 

 from it chiefly in the form of the genital segment, the presence of 

 denticles on the rostral area, the form and ornamentation of the 

 labrum, the ornamentation of the 3 elements on the mandible, the 

 armatm-e of the last segment of the endopod of leg 1 , and the form of 

 the free segment of leg 5. 



Association of the two clausidiids with the alcyonarian. — 

 Whether Hippomolgus latipes and H. cognatus live in a close association 

 with Tuhipora musica or occur only sporadically in the coral colony 



