49 

 24. Sergestes MsulcatUS, Wood-Mason. 



Sergestes bisuleatus, Wood-Mason, Ann. Mag. Nat. Hist., Feb. 1891, p. 190 and Nov. 1891, p. 353: Faxon, 

 Mem. Mus. Comp. Zool. XVIII. 1895, p. 210 : Hansen, P. Z. S. 1896, p. 919. 



Sergestes phorcus, Faxon, Bull. Mus. Comp. Zool. XXIV. 1893, p. 217 (ipso teste). 

 Illustrations of the Zoology of the Investigator, Crustacea, Plate L. Figs. 1, la-b. 



Rostrum strongly ascendant, acute, not nearly reaching halfway alone the 

 ophthalmic somite, its anterior margin a little convex near the middle. The 

 fine gastro-hepatic groove is just traceable across the dorsum of the carapace, 

 behind it the true cervical groove is very distinct dorsally. No postocular or 

 hepatic spines. 



The outer edge of the exopodite of the caudal swimmeret is setose in little 

 more than its distal fourth. 



Eyestalks not half as long as the basal joint of the antennular peduncle : 

 eye large, black, a good deal wider than its stalk. 



Antennular peduncle extremely robust in all its joints, about three-fourths 

 the length of the carapace measured in the mid-dorsal line, nearly half its length 

 being contributed by the basal joint : of the other two joints the 2nd is a very 

 little longer than the 3rd. The basal joint is hollowed for the eyes. The inner 

 (upper) antennular flagellum is at least as long as the entire body; the short 

 and slender outer flagellum, in the male, has the usual accessory prehensile 

 flagellum. 



Antennal scale a little more than half the length of the carapace measured 

 in the mid-dorsal line, its tip is rounded and its outer edge ends in a spine : the 

 flagellum is several times longer than the body. 



The 2nd maxillipeds are the stoutest of all the thoracic appendages : the 

 external maxillipeds are considerably shorter than the 3rd pair of legs and reach 

 beyond the end of the antennular peduncle : their 3 terminal joints are setose 

 on both edges. 



The 3rd pair of legs, which are the longest, reach beyond the tip of the 

 antennular peduncle ; their microscopic chela?, like those of the 2nd pair of 

 legs, are hidden in a tuft of fine seta? ; and their two terminal long-joints, like 

 the three terminal joints of the 1st and 2nd pair of legs, are setose on both 

 edges. The 4th pair of legs are considerably longer than the carapace : all 

 their four long joints are very thin and broad and have the posterior border 

 closely and very regularly fringed with seta? of extraordinary length, while 

 similar shorter (but still very long) seta? fringe the anterior border also of the 

 first two of them. The 5th pair, which are a little more than half the length 

 of the 4th, resemble the 4th in every respect, except that the constituent joints 

 are not so broad. 



Each half of the " andricum " is deeply cleft into 3 lobes (1) an inner 

 membranous portion that interlocks with its fellow of the opposite side, to form 

 7 



