igiQ-] N. Annandale & B. Prashad : Gangetic Delta Molluscs. 253 



the radula is somewhat simplified, while the shell is remarkable 

 for its small size and elongate form. These species are — A^. dene- 

 gabilis, N. orissaensis and N. ennurensis, to all of which we refer 

 in the following note, 



Nassa ennurensis, Preston. 



igi6. Nassa orissaensis var. ennurensis, Preston, Rec. Ind. Mas., XII, 

 p. 28, figs. 2, 2a. 



This form appears to us to be specifically distinct. In addi- 

 tion to the differences between it and the typical liV. orissaensis 

 noted by Preston, we may draw attention to a very distinct fea- 

 ture, well shown in his figures, in the shape of the mouth of the 

 shell, near the posterior extremity of the inner border of which there 

 is always a blunt tooth in fully adult shells of N. ennurensis, while 

 no such projection ever occurs in N. orissaensis. The typical 

 form of the former, which reaches a length of over 10 mm., has 



/ \v\#^ 



%^^ 



c. 



Text-fig. 6. — Radular teeth of brackish water species of Nassa. 



(a) N. orissaensis, Preston. (b) N. denegabilis, Preston. 



(c) N. ennurensis var. depauperata, nov. 



been recorded from the outskirts of Calcutta by Preston. A 

 smaller form with a rather broader aperture, and a much thinner 

 shell is common in the lower part of the Gangetic Delta. For this 

 form we propose the name : — 



var. depauperata, nov. 



(Plate XX, fig. 9). 



We have already stated the characters by which the shell 

 of this form can be distinguished. The animal is very like that 

 of N. orissaensis,^ but differs in the follov<^ing characters : [a) The 

 foot is proportionately narrower and a little more deeply notched 

 posteriorly, the two posterior lobes being distinctly pointed. 

 (6) The anterior processes of the foot and also the tentacles are 



' See Annandale and Kemp Mem. Ind. Miis., V, p. 34-^, figr. i. 



