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



Carapace shaped much as in Dorippe. The front consists of two 

 laminar teeth each of which again is bifid at tip : on either side of the 

 front, and separated from it by a deep cleft, is a long flat tooth or spine 

 formed by the prolongation of the antero-external angl'e of the cara- 

 pace, and forming the outer angle of the orbit. There is practically no 

 orbital floor. The antennules fold obliquely : they are large, but fold 

 fairly well into their fossae. The antennae have a long flagellum : their 

 basal joint is inserted between the eyestalk and the basal antennulary 

 joint, but on a slightly lower level. 



The buccal cavern is elongate-triangular and does not extend to 

 the front : the external maxillipeds cover only its basal three-fourths, or 

 thereabout, somewhat as in Dorippe, but the distal part is closed in by 

 stout foliaceous processes of the first maxillipeds. The flagellum or 

 palp of the external maxillipeds arises near the antero-external angle 

 of the rather broad merus, and is completely exposed in flexion. 



The afferent branchial orifices are wide openings immediately in 

 front of the bases of the chelipeds. 



The chelipeds in the adult male are often unequal : the legs have 

 the same form and relations as in Boripjoe, but the last two small and 

 dorsally placed pairs are not subchelate, although their little hook-like 

 dactylus folds backwards. The dactyli of the 1st and 2nd pairs are 

 palmulate and are very long and stout. The abdomen of the male usually 

 consists of 5 pieces, the 3rd-5th teiga being fused, that of the female 

 consists of 7 separate terga. As in Dorippe the first three terga are 

 visible in a dorsal view. 



There is very little hair about the carapace and larger appendages. 



In the Indian seas the species of this genus are, so far as is known, 

 found only at depths of between 200 and 1,300 fathoms. 



Key to the Indian species of Ethusa. 



I. Carapace ba,rely longer than broad: basal 

 antennulary joint not abnormally enlarged 

 and swollen : eyestalks freely movable : — 

 1. Branchial regions much swollen, and 

 causing a strong bulge of the lateral 

 borders of the carapace posteriorly : ex- 

 ternal orbital spines long slender acute, 

 and projecting obliquely : — 



i. External orbital spines projecting be- 

 yond the frontal spines E. indica.* 



ii. External orbital spines not project- 

 ing to the level of the frontal spines ... E. pygmasa. 



