274 Records of the Indian Museum. [Vol. XIII, 



Edwards) and S. Australia (Baker). Lenz's record from Zanzibar ^ 

 is erroneous, the specimens described belonging in all probability 

 to Desmarest's E. mathaei. 



Elamena sindensis, Alcock. 



igoo. Elamena sindensis, Alcock. Journ. Asiat. Soc. Bengal, LXIX, p. 386 

 and (1902) niusf. Zool . 'Investigator,'' pi. Ixiv, fig. 3. 



This species is still represented in the Indian Museum only 

 by the specimens described by Alcock from Karachi. In addition 

 to particulars noted by Alcock, it may be mentioned that the 

 dactylus of the male chela bears a low blunt tooth near the base, the 

 margin of both fingers being otherwise finely serrate. The dactylus 

 of the walking legs is apically triunguiculate. The abdomen of 

 the male is rather broadly triangular, its sides being Hghtly sinuous, 

 with the 3rd, 4th and 5th somites fused. The terminal segment of 

 the abdomen of the female resembles that of E. truncata. 



Subgenus Trigonoplax, Milne-Edwards. 



1853. Trigonoplax, Milne-Edwards, Ajin. Sci. nat., Zool. (3), XX, p. 224. 

 1900. Trigonoplax (subgenus of Elamena^, Alcock, Journ. Asiat. Soc. Ben- 

 gal, LXIX. p. 386. 



I agree with Alcock that Trigonoplax can only be regarded 

 as a subgenus of Elamena. E. {Trigonoplax) xavieri, which is des- 

 cribed below, still further emphasizes the close relation between 

 the two groups, the inter-antennular septum being a prominent 

 plate, exactly as in Elamena, s.s. 



In the subgenus the carapace is flatter than in Elamena, with 

 its margins scarcely at all upturned, and the chelipedes are similar 

 in the two sexes and not appreciably stouter than the walking 

 legs. In the two species of Elamena that I have seen, the ros- 

 trum is T-shaped when viewed from in front, owing to the presence 

 of a large vertical plate on its lower side ; this structure, which is 

 quite distinct from the septum between the bases of the anten- 

 nules, is either absent in Trigonoplax or is represented by a tooth 

 situated far behind the anterior margin. 



These distinctions are slight and Trigonoplax in course of time 

 will probably find a place in the synonymy of Elamena. Borra- 

 daile's E. gracilis appears from the description and figure to be 

 intermediate between the two groups here recognised, 



Elamena (Trigonoplax) cimex, Kemp. 



1915. Elamena (Trigonoplax) cimex, Kemp, Metn. Jnd. Mus., V, p. 216, 

 text-figs. 4, 5, pi. xii, fig. 3. 



The species differs from all related forms in the areolation of 

 the carapace; the gastric, cardiac and hepatic regions are each 



i Lenz, Abhamll. Senck. naturf. Ges. Frankfurt, XXVII, p. 367, pi. xlviii, 

 figs. 15 n.b ( 1902). 



