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Some observations about the male and the female from Stat. 262 will be found in the 

 description of A. semidentatiis, on the next page; both are of medium size. The carapace, 

 rostrum included, of the male is 42,5 mm. long; the rostrum, that is nearly horizontal, reaches 

 almost to the end of the antennular peduncle; the 2"'^ tooth is but little farther distant from 

 the i^' than from the 3""<i, that is situated just in the middle between the 2"<i tooth and the tip. 

 The bend at the base of the inner flagellum is already quite distinct and the petasma is already 

 developed. The external maxillipeds are just as long as the legs of the i*' pair. The rostrum 

 of the female is just as long as the carapace and the external maxillipeds are exactly as long 

 as the i^' pair of legs. In both specimens the pleurobranchia of Somite XIII is 3,5 mm. lono- 

 with 20 — 25 pairs of pinnules, almost all bifurcate. 



In these specimens from the Kei Islands the pleurobranchiae are slightly larger and their 

 pinnules are more numerous than in the other specimens that have been collected. 



The 20 specimens, finally, taken in the Bali Sea, are of all ages. In an adult female 

 the carapace, rostrum included, is 80 mm. long, the rostrum, half as long as the rest of the 

 carapace, reaches to the middle of the outer antennular flagellum. In a female, long 170 mm., 

 the pleurobranchia of Somite XIII is [,7 mm. long with 11 or 12 pairs of partly bifurcate 

 pinnules and in a male long 135 mm. this gill is i,S mm. long with 14 or 15 pairs of mostly 

 bifurcate pinnules. The 1 1 young males and females agree with those from Stat. 38. 



General distribution: Near the Philippine Islands (Spexce Bate); New Hebrides 

 (Spence Bate); Andaman Sea (Alcock). 



J 7. Aristetcs semidentatiis (Sp. Bate). 



Hemipenacus semidentatus C. Spence Bate, Report Challenger Macrura, 18S8, p. 305, PL XLIX, 



Fig. I (9). 

 Aristeiis semidentatus J. Wood-Mason, in: Ann. Mag. Nat. Hist., Ser. 6, Vol. VIII, Oct. 1891, p. 280. 

 Aristeiis semidentatus A. Alcock, Catal. Indian Ueep-Sea Crustacea, Calcutta, 1901, p. 31 ; 



Illustrations of the Zoology of the Investigator, Crustacea, PI. XLIX, Fig. 3 (cf). 



Stat. 262. December 18. 5°53'.SS., I32°48'.8E. Near Kei Islands. 560 m. Solid bluish grey 

 mud, upper laj'er more liquid and brown mud. i male and i female. 



It is with some doubt that these specimens are referred to A. scniidcntattis, because 

 according to Alcock the pleurobranchiae in advance of Somite XI\^ should be mere little 

 papillae, only visible with a lens, while both in the male and in the femak these branchiae 

 proved to be distinct filaments similar to those of A. virilis (Sp. Bate). For the rest, however, 

 they fully agree with the characters mentioned by Alcock. The male closely resembles the 

 quoted Figure 3 in the "Illustrations". The rostrum, the ujjper margin of which is slightly 

 turned downward, reaches almost to the end of 2"'' antennular article, the situation of the three 

 teeth is exactly the same as in Fig. 3. The rostral carina extends to the middle of the carapace. 

 Third abdominal somite rounded, its posterior margin unarmed. Eyes black, tubercle of the 

 eye-stalk conical, prominent. 



In the male of A. virilis the basal part of the inner antennular flagellum is distinctly 

 concave at the inner side and it appears distally, near the e.xtremity of the outer flagellum, 



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