31 



The pleurobrancliise in advance of somite XIV are distinct filaments some 

 of which may bear three or four tiny pinnules. 



In the largest female the carapace and rostrum are 82 millim. and the 

 abdomen is 98 millim., measured in the mid-dorsal line. The largest males are 

 much smaller, the measurements respectively being 50 millim. and 7S millim. 



Colour in life, blood-red. 



Andaman Sea, 271, 188 to 220, 405 fathoms. 



-r, n TV-- 856C 8572-8573 6674-6682 6684-6692 1410-1417 1481-1482 



Eegd. ^os. 6 : — — : — g : 9 : — lT j— : — To — . 



12. Aristceus semidentatus, Spence Bate. 



Hemipeneus semidentatus, Spence Bate, Challenger Crustacea Macrnra, p. 305, pi. xlix. fig. 1, J . 



Aristseus semidentatus, Wood-Mason, Ann. Mag. Nat. Ilist., Oct. 1891, p. 280. 



Illustrations of the Zoology op the Investigator, Crustacea, Plate XLIX. Fig. 3, <f . 



Resembles Aristseus virilis very closely, and differs from it only in the 

 following characters : — 



(1) the integument is glabrous and polished : 



(2) the free portion of the rostrum in the female is usually longer than the 

 carapace and is more strongly recurved ; (in the male the rostrum is short and 

 nearly horizontal, as in A. virilis) : moreover, the carina of the rostrum is lost 

 a little way behind the gastric region : 



(3) in the male the base of the inner antennular flagellum is very slightly 

 bent and twisted, and the antennal scale is not so greatly thickened at tip : 



(4) the external maxillipeds in the male are more than a dactylus longer 

 than, and in the female are at least as long as, the first pair of legs, though 

 otherwise the same as in A. virilis: 



(5) the pleurobranchiaa in advance of somite XIV are mere little papillae, 



only visible with a lens. 



Common in the Bay of Bengal at stations between 193 and 594 fathoms; 

 also in the Arabian Sea near the Laccadives and Cape Comorin, between 224 

 and 487 fathoms. 



4273-4276 6291-6302 6693-6701 6703-6711 9092 9094-9101 285-288 806-807. 



Eegd. Nos. 



7 9 9 9*9' 9 ' 10 • JO 

 1949-1955. 2122 . 3404 . 3803 . 3835. 3847. 3860-3863 



Io • "To"" "To"" io ' To - " io ' To ' 



Subgenus Hemipeneus. 



Hemipenxus, Spence Bate (part), Ann. Mag. Nat. Hist., Sept. 1881, p. 186, and Challenger Crustacea Macrura, 



p. 299. 



Aristieus, Wood-Mason (part), Ann. Mag. Nat. Hist. Oct. 1891, p. 278 (A. crassipes). 



Rostrum 3-toothed (occasionally, perhaps as an abnormality, 2-4-toothed), 

 either short in both sexes, or short in the male and very long in the female. 



