99 



e 1 Cardiac region traversed by a spinulose longitudinal ridge. 

 d l Terga of 2 nJ — 5 ,h abdominal somites marked with a single, 

 deep, transverse groove which is broadly interrupted in the 



middle. Posterior margin of hepatic groove spinulose . . Thomsoni Sp. Bate 

 (C. SPENCE Bate, Report on the Challenger Macrura, 1888, p. 185, PI. XXV, 

 fig. 1 and XXVI, fig. 1—9). 



d, Terga of 2 nd — 5 th abdominal somites presenting at each side 

 only an inconspicuous, transverse row of shallow puncta. 



Posterior margin of hepatic groove unarmed Sibogae n. sp. 



c„ Cardiac region smooth, not traversed by a spinulose, longitudinal 

 ridge. 

 Terga of 2 nd — 5 lh abdominal somites smooth, without a deep 



transverse groove Challengeri Balss 



(H. Balss, Ostasiatische Decapoden, II. Die Natantia und Reptantia. München 



1914, p. 84). 

 a 2 Carapace distinctly spinulose. 



Terga of 2 nd — 5 th abdominal somites conspicuously sculptured, though 

 otherwise than in Nephr. japonicus and andamanicus. Largest 

 spines at base of rostrum, like in Nephr. andamanicus, with 4 pairs 

 of smaller spines behind them arafurensis de Man. 



1. Nepkrops andamanicus W.-Mas. (PI. III, Fig. 15). 



Neplirops andamanicus J. Wood-Mason, Illustrations Zool. "Investigator", Part I, Crustacea, 



PI. IV, 1892 and Part II, Pi. VIII, Fig. 5, 1894. 



Neplirops andamanicus A. Alcock, in: Annals Mag. Xat. Hist. Ser. 6. Vol. XIII, March 1894, 



p. 226. 



Neplirops andamanicus A. Ortmann, in: Zoolog. Jahrb. Abth. f. Syst. Bd. X, 1897, p. 273. 



Neplirops thomsoni var. andamanica A. Alcock, A descr. Catal. Indian Deep-Sea Crustacea, 



Calcutta 1901, p. 153. 



Stat. 12. March 14. 7°I5'S., H5°is'.6E. 289 m. Bottom: mud and broken shells. 1 male, 

 bearing on the right side of the carapace a Bopyrid. 



This species, first recognized and accurately figured by Wood-Mason, has afterwards 

 been described by Col. Alcock in his "Descriptive Catalogue" as a variety of iVephrops 

 Thomsoni Sp. Bate: this fact, in my opinion, can only be explained by supposing that 

 the author of this work had 110 occasion to study specimens of the species collected by the 

 "Challenger": already in Alcock's first description of 1894 the abdominal somites of Nephr. 

 andamanicus were described as corresponding to all points with those of Nephr. Thomsoni 

 Sp. Bate, their terga being sculptured in the same way. The differences between both species 

 are, however, so important that it is quite impossible to consider Wood-Mason's species as a 

 variety of the other. 



The male, captured by the "Siboga", is 144 mm. long, while, according to Alcock, 

 this species should attain a length of 174 mm.; the carapace without the rostrum is 43 mm. 



