1917-] S. Kemp : Notes on Crusiacea Decapoda. 249 



fact that his description and figure is quoted by Milne-Edwards, 

 who, as Stebbing has remarked, probably had Desmarest's speci- 

 men before him when he wrote. Paulson's figure* differs consid- 

 erably from that given by Riippell ; the carapace is of much 

 greater proportionate length and bears grooves on its upper sur- 

 face much as in Halicarcinns and Rhynchoplax. Stebbing has 

 pointed out {loc. cit.) that Milne-Edwards' subsequent reference 

 to the species in 1853'^ is almost certainly erroneous; the genus 

 is here credited with a tridentate rostrum, a character not found 

 in Desmarest's species 



In Elamena, as represented by the species in the Indian 

 Museum, the carapace is very greatly depressed, sometimes of 

 wafer-like thinness, and the regions of its upper surface are not 

 defined by the fine-cut grooves found in the other genera. The 

 epistome is conspicuous and sometimes of great length. The ex- 

 ternal maxillipedes completely close the buccal cavern and the 

 ischium, though somewhat variable in size, is always longer than 

 the merus (see text-fig. 25, p. 276). As in Rhynchoplax the 3rd, 4th 

 and 5th segments of the male abdomen are fused, and the sutures 

 between them obliterated. The front, or rostrum, is simple, never 

 trilobate, 



I agree with Alcock^ that Trigonoplax is, at most, only a 

 subgenus of Elamena. It was described by Milne-Edwards in 

 1853/ the type species being de Haan's E. unguiformis.^ As has 

 been pointed out above, Milne-Edwards when writing in 1853 ap- 

 pears to have misunderstood the characters of his own genus 

 Elamena, and the foundation of Trigonoplax seems to have been 

 a direct result of this mistake The only constant differences 

 that I am able to find between Elamena and Trigonoplax do not 

 appear to be important and it is probable that when the characters 

 of the species are better understood, the latter will come to be 

 regarded as a synonym of the former. 



Six species of Elamena have been found on the Indian coasts 

 and are referred to below ; of these three (perhaps four) belong to 

 the subgenus Trigonoplax. Other representatives of the genus are 

 E. mathaei (Desmarest),^ the type species, found at Reunion and 

 in the Red Sea, E. producta, Kirk'' (with which E. kirki, Filhol,^ is 



I Paulson, Crust. Red Sea. Kiciv, p. 71, pi. ix, figs. 3, yi,b (1871 i. 

 ■i Milne-Rdwards, Ann. Set. iiaf.. Zoo}.. Paris (},^. X.X, p. 223, pi. xi, figs. 

 4. \a (1853). 



i Alcock, Jotirn. Asiat. Sac. Bengal. l.Xi.X, p. 38(1 (lyooi. 



* Milne-Edwards, Ann. Sci. naf.. Zool., Paris (3), XX, p. 224 (1853). 



* De Haan. in Siebold's Fauna 'Japonica, Crust., p. 75, pi. xxix, fig. i. pi. 

 H (1839). 



* For references see p. 248, tooLnotes 4. 5. FAamene truncata, Lenz (not 

 .\. M,-Ed\v.), Ahhandl. Senckenherg. Natnrforscli. Ces. Frankfurt. XXVII, i, 

 p. 367, pi. xlviii, figs. isa,b (1902) is apparently synonymous. 



■^ Kirk, Trans. N. Zealand Inst.. XI, p. 395 ( 1878) ; Filhol, Recueil de Mem. 

 Inst. France, Miss, a I'tle Campbell, Zool., p. 404, pi. I, figs, i, 2 (1885) : Chil- 

 ton, Rec. Canterbury Mas., I, p. 294 (1911). 



' F'ilhol, loc. cit. supra, p. 405, pi. xlvii, tigs. 0, 8 (1885). 



