274 CEYLON PEARL OYSTER REPORT. 



obscurely toothed : posterior angle acute (fig. 33. pi. 8 ). First segment of urus with 

 a double carina produced backwards in 2 points; 2nd segment with a small tooth and 

 a long upright spine (fig. 33. ur.). 



Upper antennae : 1st joint stout, two-thirds as long as the 2nd and about twice as 

 long as the 3rd. Flagellum long and slender, broken at the 18th joint. Appendage 

 small, with 2 subequal joints and a minute terminal one, barely reaching the end of 

 the 1st joint of the flagellum. 



Lower antenna': peduncle reaching a little beyond that of the upper; 1st joint 

 short, 2nd and 3rd subequal in length, but the 2nd much the wider; flagellum 

 shorter than the last 2 joints of the peduncle. 



Mandibles as in Elasmoj)us subcarinatus (vide '" Challenger " Amph.,' Plate 98, 

 E. iwsetosu.s), hut the 2nd joint, of the palp is subequal to and rather wider than the 

 3rd ; very tew setae (fig. 33. m.). 



First maxilla? : the inner plate oblong, with 7 plumose terminal seta? (Kg. 33. mx. 1 ). 



Maxillipeds as in E. i^ersctosus, but the outer plate reaching the end of the 2nd 

 joint of the palp. 



First gnathopods: side-plates subtriangular, with rounded angles; 1st joint stout, 

 margins parallel, as long as the 3rd and 4th united ; 2nd and 3rd subequal. Wrist 

 nearly twice as long and about as wide as the hand. Hand widening distallv, the 

 hind margin straight, the front convex and bent at the distal end at a right angle 

 round the base of the dactylus in a tooth-like process reaching beyond the middle of 

 the dactylus, and having the appearance of a 2nd dactylus; the hind margin ends in 

 a densely spinous lobe. The dactylus is very small, crooked, and deeply sunk in the 

 hand. The whole limb is setose and recalls the 2nd gnathopod of a Lysianax 

 (fig. 33. gn.i). 



Second gnathopods : side-plates deeper than wide, oblong, rounded and a little 

 wider below, about as long as the 1st joint ; this is rather longer than the next 

 3 joints, but shorter than the hand ; 2nd and 3rd joints subequal. Wrist triangular, 

 about as wide as Ions; ; the hind margin with about 8 setiferous ridges. Hand long- 

 oval, widest about one-third of its length from the base; palm undefined, the hind 

 margin densely clothed on the distal half with incurved plumose setfe. Dactylus 

 fully half as long as the hind margin (fig. 33. gn. 2 ). 



First and 2nd peraeopods : side-plates fully as deep as the segments, rounded below ; 

 hind margin of the 2nd pair concave. The entire limb is as long as the last 2 pairs 

 of perseopods, in which respect they differ from Dana's description and figure ; 

 1st joint as long as the 3rd and 4th united; 3rd longer than 4th; 4th and 5th 

 subequal, a few small spines on their hind margins ; the rest of the limb has only a 

 few scattered setee (fig. 33. pp. 2 ). 



Remaining perseopods of similar form, the 3rd rather the shortest; 1st joint wide- 

 oval, the width more than half the length, the hind margin smooth, front margin with 

 small spines; 2nd joint short ; 3rd joint very wide. 3 times as wide as the 4th. with 



