236 



Memoirs of the Indian Museum. 



[Vol. V, 



Grapsidae and Miss Rathbun' s view that it should be classed with the Varuninae has 

 much to recommend it, though it must be admitted that it is a very aberrant mem- 

 ber of the subfamily. 



Camptandrium differs from the description of the Varuninae as given by Alcock l 

 in having the sub-orbital crest and the lower border of the orbit closely adjacent and 

 in the form of the outer maxillipedes. Only a very small gap remains between these 

 appendages when they are closed and their exopod is slender and partially concealed 

 by the merus. The slender exopod forms a ready means of distingushing the genus 

 from Varuna, Ptychognathus and Pyxidognathus the only other Indian genera of Varu- 

 ninae. The hexagonal form of the carapace with its oblique and well-marked antero- 

 lateral margins gives the genus a facies very distinct from that of the more typical 

 representatives of the subfamily, to which, however, it is in some degree linked by 

 Dana's Cyrtograpsus. 



Camptandrium sexdentatum. Stimpson. 

 (Plate XII, fig. 6.) 



1858. Camptandrium sexdentatum, Stimpson, Proc. Acad. Sei. Philadelphia, X, p. 107. 



1907. Camptandrium sexdentatum. Stimpson, Smithson. Misc. Coll., XLJX, p. 138, pi. xvii, fig. 4. 



Three specimens of this species were obtained in the outer channel of the Chilka 

 Lake, two young males and a large female, the latter, although dead when brought 

 to the surface and with the carapace detached from the body, being nevertheless in a 

 fair state of preservation. The illustration on pi. xii (fig. 6) is of a young male, the 

 carapace of the female is shown in text- fig. 13. 



In most particulars the specimens agree very closely with Stimpson' s admirable 

 description ; on careful comparison with his account I am only able to detect a few 

 minor discrepancies. 



The margin of the front is slightly emarginate in the middle when viewed from 

 above and the dorsal surface of the carapace might more correctly be described as 

 unequal with only two conspicuous transverse interrupted ridges. The surface is 



finely setose in both sexes and all the more 

 elevated portions bear minute granules. The 

 anterior transverse ridge consists in reality of 

 three largish tubercles, the median of which is 

 interrupted in the middle and is placed at the 

 hinder end of the gastric region. This is clearly 

 shown in Stimpson's figure, in which the more 

 prominent ridge across the cardiac and bran- 

 chial regions is also exactly indicated. The true 

 infero-lateral margin of the carapace is visible 

 in dorsal view at the base of the last two pairs 

 of legs ; the postero- lateral margin is granular 

 and, though convex, is markedly sinuous, while 



Fig. 13. — Camptandrium sexdentatum, 

 Stimpson. 



Carapace of female. 



1 Alcock, Journ. Asiat. Soc. Bengal, LXIX, pp. 288, 389. 



