Carciuological Fauna of India. 235 



The external maxillipeds have the merus as broad as the ischium, 

 and the palp attached to the internal angle of the merus. 



The chelipeds in the adult male are somewhat stouter than the 

 other legs, have the palm short and enlarged, and the fingers arched 

 and meeting only at tip : in the female they are slenderer than the other 

 legs, have the palm slendei*, and the fingers closely apposable through- 

 out. The ambulatory legs are stout, and have the dorsal surface sharply 

 nodose or coarsely spinose. 



The abdomen in both sexes consists of seven distinct segments. 



This genus, which appears to me to be but slightly distinct from Pisa 

 (e.g., Pisa corallina), Riss., shows the transition towards Tiarinia in the 

 next group. 



That it should be grouped with Tiarinia and Macrocoehma, as it is 

 by Miers (loc. tit.), I cannot agree, since Tiarinia has complete orbits 

 and an enormously broad basal antennal joint, which Tylocarcinus has not. 



The type of Tylocarcinus, namely T. styx (Herbst) = Microphrys 

 styx A. Milne-Edwards, is placed by the latter author (Nouv. Archiv. 

 du Mus., VIII. 1872, p. 247) between Picrocerus and Criocarcinus on 

 the one hand and Hyastenus on the other; and this seems to me to be a 

 very natural position. 



Tylocarcinus styx (Herbst). 



Cancer styx, Herbst, Krabben, III. iii. 53, pi. viii. fig. 6 (" nur klein"). 



[Pisa styx, Latr. Encyc, X. 141.] 



Pisa styx, Milne-Edwards, Hist. Nat. Crust. I. 308. 



Arctopsis styx, Adams and White, ' Samarang' Crust , p. 10 ; and A. Milne- 

 Edwards, in Maillard's L'ile Reunion, Annexe F, p. 6. 



Milnia styx, Stimpson, Ann. Lye. Nat. Hist. New York, Vol. VIT. 1862, p. 180. 



Mierophrys styx, A. Milne-Edwards in Archiv. du Mus. VIII. 1872, p. 247, pi. 

 xi. fig. 4. 



Tylocarcinus styr, Miers, Ann. Mag. Nat. Hist. 1879, Vol. IV. p. 14. 



Pisa styz, Richters, Mobius, Meeresf. Maurit., p. 141. 



Tylocarcinus styx, de Man, Notes Leyden Mus., Vol. III. 1881, p. 94; and 

 Archiv. fur Naturges. LIII. 1887, p. 228 ; and Ortmann, Zool. Jahrb. Syst. etc. 

 VII. 1893, p. 62; and Henderson, Trans. Linn. Soc, Zool., 1893, p. 349. 



Carapace subpyriform and covered with rounded tubercles, among 

 which the following are distinct : — two in the inter-orbital space ; four 

 in a transverse series on the front part of the gastric region, followed 

 by three in a triangle ; one in the groove between the gastric and cardiac 

 regions, and three in a triangle on the latter region ; two, side by side, 

 on the intestinal region ; and three on the posterior margin. Besides 

 these there are several on either hepatic region, and many on the bran- 

 chial regions. 

 81 



