66 Records of the Indian Museum. [Voi.. XIX, 



side of the palp is five times smaller than the body length. The 

 anterior and posterior lips are comparatively wide (deep). 



The gills are elongated, about half the body in length and 

 thrice as long as broad. The inner gill extends a little further 

 forward beneath the labial palps and slighth^ below the outer one 

 along the antero-ventral margin. The gills do not extend into the 

 branchial siphon. The visceral portion of the gills is of the same 

 length as the portion behind. Owing to the widening out of the 

 body from side to side, and along with it the visceral mass, the 

 gills are directed more or less outward from their dorsal attach- 

 ments. The visceral portion of the inner gill is free along its 

 dorsal margin. The gills are simple and non-plicate, but they are 

 capable of much folding posteriorly owing to the presence of well- 

 developed branchial retractor muscles. 



The foot is short and stout, slightly flattened from side to 

 side and is about one-fifth the body in length. The free end is 

 somewhat dilated to form a disc-like expansion more or less con- 

 cave on the surface which presents a vertical ridge. The plane 

 of the surface is oblique to the long axis of the foot [at right angles 

 according to Preston (40)], which is directed forward and slighth^ 

 downward from the visceral mass. The retractor pedis anterior 

 muscle has a short and slender anterior and a stout long posterior 

 limb, both passing upward and backward. The fibres form a thick 

 strand in the dorso-lateral aspect of the foot posteriorly, but spread 

 out anteriorly on the inner side of the inner longitudinal muscle- 

 layer. The bifurcations of the retractor pedis posterior muscle are 

 rather short. The protractor pedis muscle is wanting. The inner 

 longitudinal layer is much thicker than the outer. The semi- 

 circular layers are not so thick. The muscles of the pedal integu- 

 ment are well-developed with numerous strands of oblique muscles 

 passing inward from the layer. Transverse muscle strands extend 

 through the entire depth of the foot, passing to the semi-circular 

 layers. At the distal end of the foot the longitudinal muscles are 

 separated into distinct bundles by the branching of the semi-circular 

 muscles and by the transverse muscles thus forming a close 

 network. 



The oesophagus is short, flattened dorso-ventrally, and is 

 horizontal in its course. The stomach is a wide irregular cavity and 

 differs greatly from that of the other members of the family. The 

 oesophageal stomach is a wide cavity receiving the oesophagus on 

 its dorsal aspect and extending in front beyond the opening of the 

 oesophagus. It is placed towards the right side of the bod}''. 

 The cardiac stomach is smaller than the oesophageal chamber 

 lying towards the left side of the visceral mass and pushing the oeso- 

 phageal stomach to the right. The central cavity is a small cham- 

 ber on the left side, separated by a vertical ridge from the cardiac 

 stomach in front and by a curved ridge from the pyloric chamber 

 behind. The p5doric stomach is a large rounded sac extending 

 posteriorly behind the origin of the coecum. The coecum of the 

 crystalline style arises from the antero-ventral aspect of the p3doric 



