1920.] B. Ghosh : Anatomy of the Solenidae. 55 



new species which is named in honour of the collector. The des- 

 cription of the shell will follow the notes on the animal. 



Animal. The body is 5 to 6 times as long as broad, nearly 

 straight both anteriorly and posteriorly, being somewhat sloping 

 in front. The anterior free margins of the mantle lobes bounding 

 the pedal aperture are thick and muscular, and present a groove 

 on their outer surface which receives a constriction of the valve 

 just behind the anterior margin. The pedal aperture extends to 

 the antero-ventral corner, and is slightly dorsal to the anterior 

 end of the anterior adductor muscle. The ventral surface of the 

 mantle is elongated and very narrow ; it presents a median band 

 along the middle line. The siphon is short and presents a longi- 

 tudinal ribbing on the surface. 



The anterior adductor muscle is long and narrow, and is 

 slightly curved. The posterior adductor muscle is small and oval. 

 The retractor pedis posterior muscle is smaller than the posterior 

 adductor muscle at its insertion. There is a well-developed 

 retractor siphonis muscle. The foot is a comparatively short 

 cylindrical organ slightly flattened laterally and presents a knob-Uke 

 swelling which ends in a blunt point at the free extremity. 



The labial palps are narrow and elongated, less than one- 

 fourth the bod}' length. 



The gills are very long and narrow, 9 to 10 times as long as 

 broad. They are half as long as the body, and are prolonged over 

 the dorsal aspect of the labial palps ; the visceral portion of the 

 gills is less than half their entire lengths. The inner lamella of 

 the inner gill is free in the visceral portion. In the cloacal portion 

 the inner lamella of the inner gills are free from each other — 

 differing in this respect from the other species of Solen and resem- 

 bling those of Ensis. 



The oesophagus is long. The anterior limb of the intestine is 

 simple, but the posterior limb presents loose folds posteriorly 

 before it forms a loop for ending in the rectum. 



Shell. The shell is very thin, translucent, ver}^ brittle, with 

 a whitish epidermis somewhat corroded in its upper anterior 

 quadrant ; length about 4 to 5 times the breadth ; anterior margin 

 nearl}^ straight and directed from above a little forward with a 

 rounded antero-superior and antero-inferior corner ; a strongl}^ 

 marked constriction just behind and parallel to the anterior 

 margin ; posterior margin straight or slightly convex, nearly 

 vertical. Umbonal teeth anterior, one in each valve. 



Anterior adductor impression narrow and elongated, with 

 tapering ends. Anterior retractor impression very small, behind 

 the anterior adductor. Posterior adductor impression small and 

 oval, at a distance from the postero-superior angle. Posterior 

 retractor impression rounded in front of the posterior adductor 

 and smaller than the latter. 



Length 16 mm. Breadth about 4 mm. 

 Type-specimen : M. ii|5s z.s.i. {Ind. Mus.). 



