240 Memoirs of the Indian Museum. [Vol. V, 



finger cleft and the upper edge of the dactylus is quite smooth, showing no indication 

 of the transverse ridges or tubercles possessed by the male. 



The ambulatory legs are a little shorter and broader than in 5. andersoni, but 

 are much more hairy than in that species ; in particular the anterior borders of the 

 carpi and propodi are covered with a dense coating of coarse setae of varying length. 

 The meral segments bear a small tooth at the distal end of their anterior margin and 

 a group of two or three teeth in a similar position on the posterior margin l . 



The abdomen of the male is decidedly narrower than in 5. andersoni. 



The length of the carapace in the largest specimen from the Chilka Lake, a 

 male, is 7-5 mm. and its breadth 9-6 mm. 



This species, which has not hitherto been found on the coast of British India, 

 belongs to the subgenus Parasesarma of de Man's terminology * and is one of a small 

 group of five species readily distinguished from the others by the presence of spines 

 on the ambulatory legs at the distal end of the posterior margin of the merus. In 

 1890 de Man (loc. cit., pp. 97, 98) gave a key to the species of Parasesarma then 

 known, three forms belonging to the andersoni group being included. Later, in 1909, 

 Caiman 8 supplied some valuable notes on the species of the group in. bis description 

 of Sesarma murrayi. Sesarma batavicum is readily separated from all its allies by the 

 use of characters derived from the chelae ; the arrangement of the ridges on the upper 

 surface of the palm and the presence in the male of a tuft of hairs in the finger- 

 cleft. 



Moreira's choice of 'batavica' as a new name for this form is not a happy one, 

 for de Man, in the same paper that contains his description of 5. barbimana, has 

 described another species of the genus under the name of S. bataviana. 



Sesarma batavicum is represented in our collection by many specimens found 

 among the clusters of shells on the oyster-bed in the outer channel opposite Manik- 

 patna. Specimens were obtained on every occasion on which the bed was examined, 

 in March, September and December, both when the water was fresh and when it was 

 as salt as the sea outside the lake. None of the females are ovigerous. 



The species is very abundant in the natural cavities of latérite blocks in the 

 Ennur backwater near Madras, where, as in the Chilka Lake, it appears to be entirely 

 aquatic in habits. It was found at Ennur also, amongst clumps of oysters. The 

 specimens are larger than those from the Chilka Lake ; the carapace of a male being 

 8 mm. long and io - 2 mm. in breadth; the collection was made in January 1915, in 

 water of specific gravity 1-0025, an( i includes a number of ovigerous females. 



The only other specimen known is the individual described by de Man and found 

 on the sea-shore at Batavia. 



1 The teeth found in Sesarma murrayi at the proximal end of this margin are not present in S. 

 batavicum. 



% De Man, Notes Leyden Mus., XII, p. 97 (1890) and Zool. Jahrb., Syst., IX, p. 181 (1895). 

 8 Caiman, Proc. Zool. Soc, London, p. 709 (1909). 



