1 

 1899.] A. Alcock — Garcinological Fauna of India. 103 



It dijffers from that species in the following particulars : — 



The carapace is more grauular, and its lobules are capped by blunt 

 conical spinules, not smooth tubercles ; and its posterior border is finely 

 and irregularly beaded, not dentate. 



The front is deeply cut into 3 spines or prongs of almost equal size, 

 not into 3 teeth of which the middle one is larger than the others. 



The eyes, though very pale, are distinctly pigmented, not devoid of 

 pigment. 



The inner angle of the wrist of tlie smaller cheliped is very strong- 

 ly spiniform, not unarmed. 



As Mr. Faxon says, Trachycarcinus is very closely related to Tricho- 

 peltarium ; in fact, the relation is so close as to make the separation of 

 the two forms almost doubtful. 



Family CORYSTID^. 



Corystiens (part) Milne Edwards, Hist. Nat. Crust. II. 139. 

 Corystoidea-Gorystidis (part) Dana, U. S. Expl. Exp. Crust, pt. I, p. 296. 

 Corystoidea (part) Miers, Challenger Brachyura, p. 210. 

 Majoidea-Corystoidea, Ortmann, Zool. Jahrb., Syst,, VII. 1893, pp. 26, 28. 

 Oxyrhyncha-Corystidas, Ortmann, in Bronn's Thier Reicb. V. ii. (Arthropoda), 

 p. 1166. 



Carapace much longer than broad, oval, convex from side to side, 

 the regions sometimes fairly well defined, sometimes not, never areolated. 



Front fairly prominent, cut into 2 or 3 teeth. 



The antennules are small and fold longitudinally. 



The antennse, when present and perfect, usually have the flagellum 

 long coarse and setaceous. 



There is no epistorae, and the external maxillipeds, which are 

 elongate and sometimes have a slight pediform cast, extend almost up 

 to the antennules. The buccal orifice is elongate and is square cut with 

 the anterior angles rounded and slightly convergent. 



Legs either all gressorial or the last pair modified for swimming. 



The following genera compose this family : — 



I. Genera in which the legs are not natatory : — 



1. Bellia, Milne Edwards, Ann. Sci. N'at. (3) IX. 1848, p. 192. 



2. *Corystes, Latr., Milne Edwards, Hist. Nat. Crust. II. 146. 



3. Gorystoides, Edwards and Lucas, Voy. Amer. Merid., Crust, p. 31. 



4. Gomezay Cray, Zool. Miscell. p. 39, Miers, Challenger Brachy- 



ura, p. 212 { = Oeidia, De Haan, Faun. Japon. Crust, p. 15). 

 6. Podocatactes, Ortmann, Zool. Jahrb., Syst., VII. 1893, p. 29. 

 II, Genera in which the legs are more or less natatory : — 



6. * Nautilocorystes, Milne Edwards, Hist. Nat. Crust. II. 149 

 ( = Dicera, De Haan, Faun. Japon. Crust, p. 14). 



7. Pseudocorystes, Milne Edwards, Hist. Nat. Crust. II. 149, 



