Carcmological Fauna of India. 283 



2. Lateral borders of the carapace gradu- 

 ally convergent without any strong bulge 

 in their posterior (branchial) part : ex- 

 ternal orbital spines short broad flat trian- 

 gular, with a mucronate tip E. andamanica. 



II. Carapace manifestly longer than broad : 



basal antennulary joint enormously enlarged 



and swollen, globular in shape, pushing the 



eyes permanently outwards : — 



1. Eyes practically immobile : chelipeds 



in the male symmetrical E. investigatoris. 



2. Eyes preserving good power of move- 

 ment : one cheliped in the male very 



markedly larger than the other E. desciscens. 



102. Ethusa indica, Alcock. 



Ethusa indica, Alcock, Ann. Mag. Nat. Hist., May, 1894, p. 405, and 111. Zool. 

 ' Investigator,' Crust, pi. xiv. fig. 2, £ . 



Carapace convex ; its extreme length, including the frontal teeth, 

 in the male only just exceeds, and in the female ecpaals, its extreme 

 breadth ; its surface is finely and closely granular almost everywhere, 

 except sometimes on the cardiac-intestinal region. 



The branchial regions are much swollen, both dorsally and later- 

 ally, the lateral swelling making the carapace more than one-tliird 

 broader across the middle of the branchial regions than across the bases 

 of the external orbital spines. The cardiac-intestinal region is small 

 and well defined, and although it is tumid it is commonly sunk below 

 the level of the branchial convexities. The anterior regions of the 

 carapace are undefined. 



The spine at the external orbital angle is broad-based, but long 

 slender and acute : it projects obliquely outwards well beyond the tips of 

 the frontal teeth. The two pairs of frontal teeth are longish and acute — 

 the outer pair being somewhat the longer: they as well as the external 

 orbital spine are a good deal concealed in a fringe of long hairs. 



The eyestalks are short slender and freely movable : the eyes are 

 often a little deficient in pigment. 



The basal antennulary joint is not abnormally enlarged. 



The chelipeds in the adult male only are asymmetrical, all the 

 joints of one side being enlarged in all dimensions : the smaller cheliped 

 is hardly as stout as the first two pairs of legs. 



The second pair of true legs are not very much longer than the 

 first : in the adult male they are a little more than three times the 



288 



