198 



all the Indian species the telson is subquadrangular and the caudal swimmerets 

 are broadly foliaceous. 



Eyestalks lamellar, the eyes, when present, lie on the dorsal surface. 



The antennular flagella, which are two in number, are of no great length. 

 No antennal scale. 



The external maxillipeds are broadly pediform or actually opercular : they 

 have no exopodite or epipodite. The 2nd maxillipeds have a flagelliform 

 exopodite and may have the rudiment of an epipodite. The 1st maxillipeds 

 have a foliaceous exopodite and epipodite. The other mouth-parts are normal, 

 the 1st maxillae having a two-jointed palp of good size, and the mandibles a large 

 incurved three-jointed palp. None of the thoracic legs have epipodites. 



The 1st pair of thoracic legs, which are chelate, are longer and much larger 

 than any of the others : one of the pair owing to the size of its wrist and hand 

 is vastly more massive than its fellow, these two joints being deep and com- 

 pressed. The 2nd pair of legs, which are subequal, are chelate, ending in a 

 broad lamellar hand. The 3rd pair of legs have an oval compressed propodite 

 and a small dactylus. The 5th pair are more or less distinctly subchelate. 



The branchiae are phyllobranchiaa and are arthrobranchiae : they are 10 in 

 number on each side, a pair being attached to the 5 somites IX-XIII. 



Key to the species of Callianassa of the Indian Oligobenthos. 



I. Carapace nearly half the length of the abdomen : eyes absent, though the 



eyestalks are well-developed ... ... ... ... G. cseeigena. 



II, Carapace not quite a third the length of the abdomen: eyes present ... G. lignicola. 



115. Callianassa ccecigena, Alcock and Anderson. 



CalUanatsa cascigena, Alcock and Anderson, Joarn. Asiatic Soc. Bengal, LXIII. pt. 2, 1894, p. 163. 



ILLUSTRATIONS OF THE ZOOLOGY OF THE INVESTIGATOR, CRUSTACEA, PLATE XXVI. FlG. 2. 



Belongs to M. Milne-Edwards' first section of the genus (A. Milne-Edwards, 

 Nouv. Archiv. du Mus., VI., 1870, p. 75), in which it stands alone in having no 

 trace of corneas, although the eyestalks are well developed and of the usual 

 form. It is otherwise close to C. gigas, Dana. 



The carapace, which is a little less than half the length of the abdomen, is 

 of the typical form, and ends in an acute triangular rostrum that reaches to the 

 end of the eyestalks these not reaching to the end of the basal joint of the 

 antennular peduncle. The middle of the three segments into which the carapace 

 is longitudinally divided is gently carinated, the carina culminating, near the 

 posterior border, in a large strong upstanding tooth. Of the abdominal terga 

 no two are at all alike either in size or shape. The first, which is the narrowest 

 and by far the shortest and has all its angles cockled upwards, is not two-fifths 



