342 A. Aleock — Oarcinoloyical Fauna of India, [No. -3, 



The Xanthasia sp., or Xanthasia Whitei, from Mergui, referred to 

 by de Man in Journ. Linn. Soc, Zool., XXTT. 1887-88, p. 106, pi. vii. 

 fig. 1 is represented in the collection by a single small male and is 

 characterized by having the upraised edge of the carapace blunt and 

 rounded, instead of thin and acute, and the median tubercle of the 

 carapace ill defined instead of sharply circumscribed : the posterior 

 margin of the carapace, also, is more prominent and is not quite contin- 

 uous with the lateral margins. The legs also are somewhat longer. 



Family OCYFOBWM, Ortraann, emend. 

 Key to the Indian genera of Ocypodidae. 



I. A hairy-edged pouch leading into the branchial cavity, 

 between the bases of the 2nd and 3rd pair of true 

 legs [Ocypodinse] : — 



1. Antennalar flagella rudimentary, completely 

 hidden beneath the front : antennae small, 

 almost rudimentary : eyes very large, occupy- 

 ing the greater part of the ventral surface of 

 the eyestalks : chelipeds very unequal in both 



sexes Ocypoda. 



2. Antennalar flagella small, not hidden beneath 

 the front : antennas of good size : eyes small, 

 terminal on the long slender eyestalks : in the 

 male only, one cheliped is enormously enlarged 



the other being very small Gelasimus. 



II. No pouch or opening between the bases of any of the 

 legs :— 



], The antennules fold obliquely or nearly 

 vertically : curious membranous spaces, or 

 "tympana," are present on the meropodites 

 of the legs {Scopimerinse) : — 



i. Tympana very well defined : external 

 maxillipeds very large and with a strong 

 almost hemispherical bulge forwards : — 



a, Merus of external maxillipeds larger 

 than the ischium : the distal end of 

 the 4th abdominal segment of the 

 male is fringed with bristles and 

 overlaps the 5th segment Dotilla. 



b. Ischium cf external maxillipeds 

 larger than the merus : the 4th 

 abdominal segment of the male is 

 normal, but the 5th is constricted 

 in part or all of its extent and gives 

 the abdomen a wasp-like appear- 

 ance Scopimera. 



