I9I3-] Ekendranath Ghosh : Mollusca, I. 223 



flap is fused with the lower tentacle at the inner side, being 

 slightly grooved on the inner aspect for the reception of the 

 ommatophore. The infero-external surface is directed downwards 

 and outwards, and lies on a thin flattened process of integu- 

 ment placed over the lateral aspect of the anterior surface of the 

 foot. The infero-internal surface is directed downwards and in- 

 wards and is continuous behind with the lining of the cavity leading 

 to the mouth. The anterior border is thick. The outer border is 

 also thick. The inner border gives attachment, at its back, to an 

 integument which forms the dorsal wall of the cavity mentioned 

 above. The inferior border is continued at its base to a transverse 

 ridge of integument, which forms the inferior boundary of the 

 cavit}' leading into the mouth. 



The lower tentacle is fused with the precephalic flap except at 

 the rounded tip. 



A thin flap of integument extends transversely below the 

 cavity leading into the mouth, forming its ventral wall. On either 

 side it is attached to the inferior border of the precephalic flap at 

 its base. From the attachment of this membrane to the pre- 

 cephalic flap, arises a thin integument which at once ends in a 

 triangular process on its upper aspect. The triangular process is 

 attached behind to a thin band extending, from the outer aspect of 

 the head at its posterior end, downwards to the side of the foot at 

 its anterior end. This post-cephalic band is bounded behind by a 

 groove which is a continuation of what forms the boundary between 

 the head and the bod3^ This band forms the dorsal wall of a slit- 

 like cavity into which the pedal gland opens. 



The mantle is attached to the dorsal surface of the body about 

 '2 cm. behind the head. The line of attachment then passes for- 

 wards and downwards to come within '5 mm. of the groove behind 

 the head, at the level of the lower border of the precephalic flap ; 

 then it runs parallel to the groove behind the band (just described) 

 and ends in the groove between the foot and the margin of the 

 mantle. 



The foot is widest at a point '3 cm. from the anterior margin 

 and tapers very gradually to a point at the posterior end. The 

 foot projects beyond the mantle border for about "la cm. at 

 its posterior end. The anterior end of the foot forms a concave 

 surface, the lateral borders of which are sloping from above down- 

 wards and backwards for about '2 cm. from the anterior margin. 

 The sole is finely wrinkled in a transverse direction, the margin of 

 the sole forming a thick rim. 



Measurements (iu cm.) 



Length along the middorsal line of the mantle . . 4'0 



Length along the midventral line . . . . 2-7 



Greatest height (at the junction of the anterior one- third 



and posterior two- thirds) . . . . . . 7 



Greatest breadth . . . . . . • • 75 



