50 A. Alcock — Carcinological Fauna of India. [No. 1, 



diameter is nearly half the width of the 

 interorbital space : first tooth of antero- 

 lateral border anteriorly truncated and 



notched , G. miles. 



B. A transverse ridge on the cardiac region, as 



well as one or two in the posterior half of either 



branchial region : — 



1. Two additional ridges in the posterior 

 half of either branchial region ; all the 

 spines of the antero-lateral border well 

 developed : — 



a. Carapace moderately broad : first 

 spine of antero-lateral border trun- 

 cated, th.e last not enlarged : orbits 

 without dorsal inclination : cheli- 

 peds strongly granular and nodular G. natator. 



h. Carapace very broad : last spine 

 of the antero-lateral border twice 

 as long as any of the others : orbits 

 with strong dorsal inclination : a 

 stout tooth on the lobule of the hasal 

 antenna- joint G. variegatum, 



2. One additional ridge on either branchial 

 region : second spine oj antero-lateral 



h order rudimentary G. orientale. 



C. A transverse ridge on the cardiac region, but 

 none on the posterior half of the branchial 

 region : — 



1. Carapace flat : 3 spines on anterior border 

 of arm, 5 on upper surface of hand : sides 

 of 6th abdominal tergum of male curved 



and gradually convergent G. afUne. 



2. Carapace convex : 2 (hardly ever 3) 

 spines on anterior border of arm : — 



a. Carapace about two-thirds as long 

 as broad : 8 spines on the hand : 

 sides of 6th abdominal tergum of 



male parallel for half their extent G. callianassa. 



b. Carapace about four-fifths as long 

 as broad : 2 spines on the hand : 

 sides of 6th abdominal tergum of 

 male curved : the two middle 



frontal teeth remarkably prominent G. rostratum, 

 II. Antenna! flagellum completely excluded from orbital 

 hiatus : posterior border of dorsum of carapace straight 

 and forming a dog's-eared angular junction with the 

 postero-lateral borders : the posterior border of the 

 arm ends in a spine (Goniohellenus) : — 

 A. Last spine of the antero-lateral border smaller 



than any of the others G, ornatus. 



