250 Records of the Indian Museum. [Vol. XVI , 



Assiminea brcvicula (Pfr.). 



1 88;. Assiminea brevicula, Bottger, op. cit., p. 163. 

 1897. Assiminea brevicula, von Martens, op. cit., p. 213. 



Further references will be found in the papers cited. 



We have nothing fresh to say about the shell or the living 

 animal. We figure the radular teeth (fig. 4^), they are not unlike 

 those of A. violacea as figured by Heude,' but the upper part of 

 the central tooth is still more constricted, its cusp is larger, and it 

 has four basal ilenticulations on each side ; the denticulations of 

 the lateral teeth are also better developed. 



The species is very common on mud between the tide-marks 

 in the lower part of the Gangetic Delta. Its distribution extends 

 from the estuaries of the Ganges to those of Central China. 



Assiminea beddomiana, Nevill. 



1881. Assiminea beddomiana, Nevill, Jouvn. As. Soc. Bengal, L (iij, 

 p. 158, pi. vii, fig. 3. 



The animal is very like that of A. brevicula, but the radula 

 differs considerably (fig. 4ft), in that the upper part of the 

 central tooth is not constricted, the denticulations at its base are 

 feebly developed and its cusp is smaller. The denticulations of 

 the lateral teeth are also less well developed, and those of the 

 marginal, which is more symmetrical, are much smaller and more 

 numerous. 



This species occurs with A. brevicula, but is much less abun- 

 dant. It is only known from the estuaries of the Ganges and the 

 Irrawady and from intermediate localities. 



Assiminea ( ? Cyclotrophis) francesiae (Gray). 

 (Plate XX, fig. 7). 



1887. Assiminea francesi, Bottger, op. cit., p. 176. 



The shell of A. jrancesiaz is, as Bottger points out, extremely 

 variable. We do not think that the different forms named by 

 Nevill as varieties or sub-varieties should be regarded as distinct. 

 At some localities, however, notably at the edge of the river Pussur 

 at Khulna, many adult shells have a number of ridges or varices 

 running across the lower part of the body- whorl and probably rep- 

 resenting periods of aestivation. 



The radula (fig. ^c) differs considerably from that of the two 

 species we have just discussed, and also from that of A. scalaris, 

 Heude, which on shell characters alone comes in the same group.* 

 The chief differences are : (a) there is a minute but elongate bifid 



' Op. cit., XXI, fig. 4c. 



2 See Heude, op. cit., XXI, fig. 5, We have examined a radula of this 

 species and find that while there are small variations in the denticulation of the 

 teeth, the general outline as shown in Heude's figure is correct. 



