240 CEYLON PEAEL OYSTER REPORT. 



First gnathopods : 1st joint with almost parallel margins, as lung as the next 4; 

 2nd as wide, about one-fourth as long as the 1st and longer than 3rd or 4th ; the 

 3rd overlapping the 4th, cordate, the point distal, hind margin very convex ; wrist 

 rather shorter than the hand, widening distally ; base of the hand as wide as the 

 wrist, narrowing to the dactylus ; the latter short, curved, with a secondary tooth 

 near the point. All the joints, except the 1st and Gth, have long setae on the hind 

 margin. Side plates subrectangular with rounded angles, wider than the next two 

 (fig. 4. gn. 1 ). 



Second gnathopods : 1st joint about as long as the next 3, curved and widening 

 distally ; 2nd almost as long as the 4th, with 2 or 3 long stiff setae in a depression on 

 the hind margin near the distal 'end ; 3rd very convex, with a group of erect setae on 

 the hind margin. Length of wrist to hand as 5 : 3. the former narrow, hind margin 

 slightly concave, with short setae and scanty fur at the distal end : the hand widens 

 gradually to the end, furred on the hind margin, with short seta? on the front and a 

 tuft of long setae at the base of the dactylus ; this is strong and overlaps the hind 

 margin (fig. 4. gn. 2 ). 



First and 2nd peraeojeods slender, with few setae and no spines. 



Third peraeopods : side plates wider than deep, lobes equal, larger than the 1st joint, 

 which is suborbicular, flattened behind, margins smooth, a few seta; on the lower part 

 of the front. 



Fourth peraeopods : the 1st joint flattened behind, the lower part of the front 

 margin spinous; the upper part of the hind margin faintly serrate. 



Fifth peraeopods : the 1st joint rounded and more distinctly serrate behind, spinous 

 on the lower part of the front margin. 



First uropods spinous, the rather slender peduncle considerably longer than the 

 subequal rami. 



Second uropods : peduncle wide at the base, narrowing distally and about as long- 

 as the outer ramus, which is rather longer than the inner and spinous; the inner has 

 one spine near the end (fig. 4. up. 2 ). 



Third uropods : peduncle longer than the rami, with 2 or 3 spines and a distal tooth 

 on the outer margin ; outer ramus rather the longer, without a terminal joint, with 

 2 spines dividing it into 3 equal parts (fig. 4. up. 3 ). 



Telson about half the length of the peduncle of the 3rd uropods, oval, deeply 

 emarginate at the end, with a, short spine on each of the lobes (fig. 4. ur.). 



This genus differs from Amaryllis in the presence of a palp to the 1st maxillae and 

 in the smaller side j>lates of the first 4 segments. From Socarnes it differs in the 

 mandibles, maxillipeds, 2nd gnathopods, telson, and 3rd uropods. It may be 

 considered as connecting those two genera. The excavated point of the telson 

 separates it from Lysianax, though Della Vallk (loc. cit., p. 7S'.). plate 25) has 

 described a species under the' name of L. punctatus with a similar telson. From this 

 the present species differs in the antennae, 1st maxilla 1 , &c. 



