I9 T 5-] Fauna of the Chilka Lake : Crustacea Decapoda. 301 



boulders, which under certain conditions of flood, tide and wind are above water- 

 level. According to our observations the specific gravity of the water in this part 

 of the lake varies from roo6 to 1-015. Our collections show that the species occurs 

 in both localities throughout the year. 



Ovigerous females were found at the south end of the main area in March and, 

 on the oyster beds in the outer channel, in September and December. The eggs are 

 a little more than -5 mm. in diameter. The largest individual is about 36 mm. in 

 length. 



An individual from Rambha Bay was, in life, of a dull greenish colour with 

 darker green markings on the large chela ; there was also a small black spot on each 

 side of the second and fourth abdominal somites. In the large chela the tips of the 

 fingers are pink. 



This species does not construct an elaborate burrow, although when found under 

 stones on soft mud it appeared to have excavated a short horizontal tunnel, probably 

 never more than a few inches in length. The sound made by the species is very loud 

 and we frequently heard it when walking near the places in which specimens were 

 living. 



Alpheus crassimanns is known to have a distribution extending from Djibouti 

 to Celebes. 



Alpheus malabaricus, Fabricius. 



1798. Alpheus malabaricus , Fabricius, Ent. Syst. Suppl., p. 405. 



1893. Alpheus malabaricus, Henderson, Trans. Linn. Soc, Zool. (2), V, p. 434, pi. xl, figs. 1-3. 

 1911. Alpheus malabaricus, de Man, Rep. ' Sibo^a' Decapoda, II, Alpheidae, p. 330 (in key to 

 species). 



In his account of the ' Siboga ' Alpheidae de Man recognises two varieties of this 

 species, var. dolichognathus , Ortmann, and var. leptopus, de Man, and the characters 

 by which these three forms are differentiated are shown in his key. 



The specimens from the Chilka Lake unquestionably represent the typical form 

 of the species and agree precisely with Henderson' s description. It is also clear, 

 from de Man' s key, that they should be referred to this form; but the carpocerite l 

 resembles that of A. macrodactylus , Ortmann, being equal in length with the anten- 

 nular peduncle. 



In the large chela of the specimens from the Chilka L,ake the proportion of length 

 to breadth is apparently variable; it is 36 times as long as broad in an adult female, 

 276 times in an adult male and 3 16 times in a younger male. In the third pair of 

 legs the merus is nearly 7 times and the propodus about 10 times as long as broad. 



On the whole the typical form seems to resemble the var. leptopus more nearly 

 than the var. dolichognathus ; but in the former variety, as shown in de Man's key, 



1 By the term carpocerite I understand the fifth segment of the antennal peduncle {see Caiman in 

 Lankeshr' s Treatise on Zoology, Crud., p. 265, text-fig. 156B, 1909) and I am unable to understand de 

 Man's reference {op. cit., p. 430, para. 2) from which one would gatner that the carpocerite is composed 

 of three segments. 



