286 A. Alcock — Carcinological Fauna of India. [No. 2, 



convexities being granular : the rest of the carapace is somewhat con- 

 cave. 



The chelipeds and ambulatory legs are rough : the chelipeds have 

 the lower edge sharply dentate, and the outer edge of the carpus sharp- 

 ly dentate : the ambulatory legs have the 3rd, 4th and 5th joints cari- 

 nate or cristate above, and the 3rd and 5tb joints cristate below : the 

 dactyli are cristate on both edges, and end in little claws. 



The abdomen is deeply sculptured. 



In the Museum collection is a male from the Andamans, and a 

 female from Ceylon. 



Sub-family II. EUMEDONIN^E, Miers. 



Miers, Journ. Linn. Soc, Zool., Vol. XIV. 1879, p. 670. 



Carapace rhomboidal or pentagonal, with a spine at the junction of 

 the antero-lateral and postero-lateral borders. Rostrum usually bifid 

 or emarginate. Surface of carapace nearly flat. Chelipeds of moder- 

 ate size and length. 



Key to the Indian genera of the sub-family Eumedonin^;. 

 I. Floor of the orbit not in contact with the front, but leaving 

 a hiatus which is more or less filled by the second joint 

 of the antennal peduncle. Chelipeds armed with large 

 spines : ambulatory legs compressed : — 



1. Spine of antero-lateral angle of carapace direct- 



ed forwards Zebrida. 



2. Spine of antero-lateral angle directed straight 



outwards; last pair of legs dorsal in position... Eumedonus. 

 II. Floor of the orbit meeting the front, so as to completely 

 exclude the antennal peduncle from the orbit : chelipeds 

 not armed: ambulatory legs not compressed Ceratocarcinus. 



Zebeida, Adams and White. 

 Zebrida, Adams and White, ' Samarang ' Crustacea, p. 23. 

 Zebrida, Miers, J. L. S., Zool., Vol. XIV. 1879, p. 670. 



Carapace sub-rhomboidal, flattened, with the rostrum formed by 

 two large, acute, laminar, almost parallel teeth ; and with the antero- 

 lateral angles produced to form two similar laminar teeth projecting 

 forwards in a plane parallel to the rostrum. 



Orbits circular, their inner canthus being filled by part of the 

 antennal peduncle. 



The antennules fold obliquely. The antennse are entirely concealed 

 beneath the rostrum : their flagellum is well developed ; and their 

 basal joint is longish, reaching to the inner canthus of the orbit. 



