igsi.] N. Annandale & R. B. S. Seweli, : Vivipara. 219 



and to the outerside of the tentacle is a small narrow fold with a 



rounded anterior margin and a free external border ; this forms a 



gutter in which the base 



of the right tentacle and 



the right eye rest. As we 



trace the fold forwards 



and backwards it is seen 



to commence on the under- 



surface of the snout close 



to the junction of the 



snout and foot ; it then 



runs backwards along the 



right side of the snout K,e. ,. —Living V. bengaUnsis extended 



and near the base of the from the shell as fully as possibly. 



tentacle it curves out- 

 wards and forwards and becomes continuous with the syphon. 

 The syphon is formed b}- a thin leaf-like process the two edges 

 of which are curved upwards so as to form a tube, which is 

 exhalent in function. The mouth of the syphon looks outwards 

 and downwards and when ixxWy extended, backwards. The inner 

 fold of the syphon is continued backwards and becomes continu- 

 ous with the branchial fold, which passes backwards and towards 

 the left on the floor of the branchial chamber. The whole of the 

 upper surface of the foot and the head as well as the epipodia 

 and syphon are covered with ciliated epithelium ; the only region 

 devoid of cilia is the clear cornea of the ej-es. The head is 

 heavily pigmented with black, variegated with dots and splashes 

 of golden-yellow in varying degrees of intensity. In examples 

 taken from the tank in the Indian Museum compound the snout 

 is frequently an almost uniform black, unrelieved by any lighter 

 pigment and in some cases the tentacles are alternately banded 

 in yellow and black. The syphon is as a rule of a golden colour. 



The part of the body enclosed withitr the shell is the visceral 

 hump and in a fuUy-grcwn example possesses 5J — 6 spiral whorls. 

 The skin covering the visceral hump also shows a certain degree of 

 pigmentation, which varies however in different areas as well as in 

 different individuals. In the upper whorls it is often of a deep 

 black colour, while in the lowest or body-whorl the pigment usually 

 follows the lines of the blood sinuses, but as a rule the males are 

 more heavih' pigmented than the females. The upper a-g- — 3 body- 

 whorls are occupied by the liver and the stomach : this latter 

 organ appears on the surface between the lobes of the liver on the 

 right and posterior aspects of the 3rd body-whorl. The penulti- 

 mate body-whorl, when viewed from above, is seen to be occupied 

 on the left side by a loop of intestine, in front of which is an area 

 of thin skin separating it from the kidney and the upper end of 

 the testis in the & or the albumen gland and shell gland in the $ . 

 The whole of the lowest or body-whorl is occupied by the bran- 

 chial chamber, and a series of organs extend throughout its whole 

 length attached to its thin roof. On the extreme left of the 



