350 DE. AY. T. CALIIAX OX XEW OE EAEE 



CcMELLA L^vis, sp. n. (Plate XXXII. figs. 25-27.) 



Description of adult Female. — Total length 1-15 mm. 



Carapace a little more than one-third of total length, its depth more than half its 

 length. Dorsal edge horizontal, slightly sinuous, without teeth. The ocular lobe is 

 prominent on the dorsal surface and the eye is pigmented. The pseudorostrum is very 

 short and truncated, the lateral plates meeting in front of the ocular lobe for a distance 

 less than the diameter of the lobe. The straight antero-lateral margin slopes backward 

 and the angle is obtuse and rounded. The surface of the carapace and of the rest of 

 the body is without conspicuous hairs. 



The abdomen is shorter than the cephalothoracic region. The last somite is less 

 than two-thirds as long as the preceding, not inflated ; seen from above it is little 

 longer than broad and its broadly rounded posterior lobe projects only for a short 

 distance between the bases of the uropods. 



The antennules have the peduncle rather stout, the last segment being about two 

 and a half times as long as wide and shorter than the preceding segment ; the inner 

 fiagellum is minute and unsegmented. 



The. first legs have the basis about half as long as the remaining segments ; that of 

 the second legs is more than two-thirds as long as the remaining segments. 



The remaining legs are short and stout ; the last pair are little more than two-thirds 

 as long as the carapace and have the carpus about one-half longer than the raerus and 

 little more than half as long as the basis. 



The uropods have the peduncle nearly twice as long as the last somite. The sub- 

 equal rami are more than two-thirds as long as the peduncle and each bears a slender 

 terminal spine sharply marked off from it. There are four spines increasing in length 

 distally on the inner edge of the endopodite. 



Occurrence.— Gxxli of Siam, "Koh Kam, 1-5 fathoms, 1/1/00, 6/2/00," "Between 

 Koh Mesan and Cape Liant, 5-8 fathoms, 7/2/00." Th. Mortensen Coll., Copenhagen 

 Museum. Co-types in British Museum. 



Genus Nannastacus. 



The discrimination of species in this genus presents difficulties which I have not been 

 able altogether to overcome. The collection of the Copenhagen Museum comprises 

 a very large number of specimens of Xcninastacus, most of which were collected in the 

 Gulf of Siam by Dr. Th. Mortensen. The great majority of these are males resembling 

 in general characters the male of N. zimmeri described below, but diftering among 

 themselves in size, in tlie proportions of the uropods and legs, in the relative size of 

 the eyes, and in other small characters. Most of these characters are subject to 

 individual variation, and after dissecting, drawing, and comparing a number of these 

 males I have reluctantly come to the conclusion that it is impossible, at present, to 

 group them under specific names or to pair them with the different forms of females. 



