CETISTACEA. OP THE MERGTJI ARCHIPELAGO. 119 



developed, the inner margins of the fingers are not armed with 

 the three or four prominent teeth which occur in the type, but 

 present only some small equal granules, especially in their distal 

 halves. 



This common Indian species has been collected throughout the 

 whole Indian Ocean, the Malayan Archipelago, and the Pacific 

 Ocean, having been recorded from Zanzibar, Mozambique, Nossi- 

 Be, Madras, Ceylon, Nicobar Islands, Java, the Philippines, 

 Moluccas, New Guinea, the Piji Islands, and Tahiti. 



74. GrEI/ASiaiUS TBlATSGrJJLAUia, A. M.-JEdw. (PI. VIII. figs. 

 8-11.) 



Gelasimus triangularis, Alph. M.-Edwards, Crustaces de la Nouv, Cale- 

 donie, Nouv. Arch, du Museum Hist. Nat, t. ix. p. 275. 



Gelasimus perplexus, Heller, Crustaceen der Novara-Reise, p. 38, Taf. v. 

 fig. 4 (wee Milne-Edwards). 



Thirty-three specimens (24 c? , 9 $ ) were collected, five of 

 which were found at Kisseraing Island, the other specimens 

 being without a definite locality. 



This form belongs to the same section of the genus as the 

 preceding species. In the shape of its cephalothorax it stands 

 in the same relation to Cf-elas. annuUpes, M.-Edw., as G-elas. acutus, 

 Stimps., does to Gelas. vocans, M.-Edw. The carapace of Gelas. 

 acutus is much more narrowed behind than that of Gelas. vocans, 

 and the cephalothorax of Gelas. triangularis is much more 

 narrowed posteriorly than that of Gelas. annulipes. 



The specimens have been compared and identified with a 

 typical specimen of G. triangularis from Kew Caledonia, in the 

 Paris Museum. 



I will now describe this species and compare it at the same 

 time witb Gelas. annulipes. The cephalothorax is strongly 

 convex and arcuate longitudinally, and much larger in front than 

 at the posterior margin. The upper surface appears perfectly 

 smooth and presents no interregional grooves, so that the grooves, 

 which in G. annulipes separate the gastric from the branchial 

 and cardiac regions, are absent in this species. The median 

 frontal groove is also scarcely visible and less distinct than 

 in G. annulipes. As regards the shape of the front, both 

 species agree with one another ; in both it appears a little punc- 

 tate when examined under a magnifying-glass. 



