IÇI5-J 



Fauna of the Chilka Lake : Crustacea Decapoda. 



237 



the posterior margin, also granular, is perfectly straight and terminates in a rec- 

 tangular or acute angle on either side. Of the teeth on the antero- lateral margin 

 the first (which corresponds with the outer orbital angle) and the third are more or 

 less acute ; the second is smaller and bluntly rounded. The teeth are sharper in the 

 young males than in the adult female. The upper orbital margin is conspicuously 

 elevated, both at the side of the front and behind the eye, the latter border being 

 strongly sinuous. The lower border of the orbit, as Stimpson has explained, bears 

 a small dentiform lobe internally ; the margin is well developed and not deficient as 

 in Varuna. 



The external maxillipedes are precisely as described by Stimpson. Compared with 

 Miss Rathbun' s figure of the appendage in C. paludicola, the ischium is more quad- 

 rate, equal in length to the merus, and the division between the two segments is 

 straighter and more oblique (text-fig. 14). 



The chelipedes in all the specimens are small, weak and shorter than the carapace. 

 The carpus is a little shorter than the palm. The chela is very slender and the 

 fingers are about as long as the palm in the female, a trifle longer in young males. 

 They are slightly curved in dorsal view and are 

 very deeply channelled internally throughout their 

 length, so much so that each resembles a greatly 

 elongated spoon. 



The first and last walking legs are about equal 

 in length — a little longer than the carapace ; the 

 second and third pairs are about one and three 

 quarters the length of the carapace. The merus is 

 more slender than is shown in Stimpson's figure; 

 the ridge near the upper margin is conspicuous and 

 granular. The upper edge is also granular and in 

 young males bears a minute subterminal spinule on 



the two middle pairs, much smaller than that found in C. paludicola and apparently 

 wholly absent in the female. The inferior surface of the merus is provided with two 

 granular longitudinal ridges separated by a comparatively broad interspace. The 

 dactyli are about equalin length with the propodi. 



The sternum agrees exactly with Stimpson's description. In the young males 

 the abdomen has a wavy outline, the margin being concave opposite each sternal 

 segment and convex opposite the interspaces of the segments; it could hardly 

 be described as "strongly constricted and sinuated on each side at the middle", 

 but the form is probably subject to change during growth. Except for the most 

 distal one, the sutures between the abdominal segments can scarcely be detected in 

 the larger male example, they are more distinct in the small individual. The sutures 

 in the abdomen of the adult female are conspicuous and markedly sinuous in the 

 middle. The margin of the abdomen is, in this sex, thickly fringed with plumose 

 hairs and, in all the specimens, a number of similar hairs are to be found on the 

 walking legs. 



Fig. 14. 



-Camptandrium sexdentatum, 

 Stimpson. 



Third maxillipedes of young male. 



