1920. | B. PRASHAD: Anatomy of Corbicula. 20 
The palps are comparatively short, fleshy structures some- 
what triangular in outline and the two palps of each side are of 
about the same size. The abdominal mass is much larger com- 
paratively than that of C. lagillierti. ‘The foot is small and feebly 
developed, it is rounded posteriorly and has a slightly pointed tip 
on the anterior side. The rest of the digestive system is very 
similar to that of the genus Galatea.! The rectum and the heart, 
lying in the pericardium, are plainly visible through the mantle. 
There is nothing special to note about the nervous, circulatory 
and excretory systems. Regarding the genital system the only 
point of interest is the more swollen condition of the abdominal 
mass in the females. 
Affinities, etc. The animal closely resembles that of C. lagil- 
iertt described by Fischer (loc. cit.), only differing in the better 
development of the siphons, the abdominal mass and the palleal 
muscles. The siphonal muscle is poorly developed and the palps 
are much smaller. These differences may possibly be correlated, 
as Dr. Annandale has suggested to me, with the peculiar conditions 
in which Corbicula fluminalts is found. These are its living buried 
in soft mud and the long period of hibernation during the dry 
weather. 
Fischer’s remark as to the main distinguishing characters of 
the genus Corbicula, when he says, “ On distinguera aisément les 
cyrénes a levrs branchie non réunies en arriere avec celles du cété 
opposé,’’ is far from a correct description for, as has been des- 
cribed, the inner lamellae of the inner pair of gills of the two sides 
are united with each other in the posterior part and are not free. 
Fischer himself had recognized this, for in his ‘‘ Manuel de Conchy- 
liologie ’’ (p. rogr) he described the animal of the genus Corbicula 
as having “‘ branchie réunies en arriére.’’ 
! Rang in Ann. Sct. Nat. XXII, pp. 152-164, pl. v (1832). 
