2i8 Records of the Indian Museum. [Vol. XXII, 



The main mass of the foot is divided into two layers. The 

 lower laj'er, which forms the sole and consists of soft greyish- 

 coloured spongy tissue, is tra- 

 versed by a network of muscle- 

 fibres, which is in turn covered 

 by a layer of columnar epithelium. 

 [It is this tissue that forms the 

 whole surface on which the ani- 

 mal crawls]. The upper and 

 posterior portion of the foot is 

 composed of white muscle-fibres. 

 This mass of muscle, which arises 

 , . . , r ,- , , from the operculum, becomes 



hiG. I. — Living male ot 1 . benp-aleii- ^. .,, ,, , ,, 



SM as s?en from below. contmuous With the columellar 



muscle, which runs upwards in 

 the floor of the mantle chamber and is inserted into the 

 columella about half-a-turn of the spiral above the mouth of 

 the shell. Between the sole and the opercular muscle is a layer 

 of tissue, consisting of a somewhat open reticulum, the meshes of 

 which enclose numerous irregular spaces, and lying free in these 

 are oval or rounded deeply-staining bodies, which closely resemble 

 starch grains. Similar bodies are also found scattered through the 

 reticulate tissue of the edge of the mantle. Between the two 

 tissues of the foot the pedal nerves and the terminal portion of 

 the cephalic artery pass backwards, and the central region is also 

 occupied by a large venous sinus, running antero-posteriorly in 

 the middle line. 



The anterior part of the body forms a well-marked ' head,' 

 which is produced forwards in the middle line in a short trunk- 

 like snout, on the anterior and central aspect of which lies the 

 oral aperture. Projecting upwards and forwards on either side of 

 the base of the snout is a slender tapering tentacle. Each tentacle 

 arises from a short thick base which is produced on the outer side 

 in a short wide pedicle bearing at its tip a well-marked globular, 

 pigmented eye. Each eye is hemispherical in outline and is situ- 

 ated on the anterior and inner aspect of the pedicle. It consists 

 of a clear cornea superficially, which is usually outlined with golden 

 3'ellow pigment, and the optic cup is lined by a black, heavily- 

 pigmented retina and encloses an almost spherical lens. 



In the female both tentacles are s.ymmetrical, but in the male 

 the right tentacle is somewhat thickened and is curved in a sickle- 

 shaped manner. In this latter sex this tentacle is traversed through- 

 out its whole length by the ejactulatorj' duct, which opens through a 

 small orifice at the extreme tip. The whole tentacle forms an intro- 

 mittent organ or penis. Immediately behind and below the base of 

 the tentacles the bod}- surface is produced on either side in a fold — 

 the epipodium. On the left side, the epipodium is triangular or 

 quadrate in shape and is prolonged backwards along the side of 

 Ihe head almost to the point of origin of the mantle. On the 

 right side the epipodium is more complex. Immediately below 



