1920.] E. Ghosh : Anatomy of the Solenidae. 57 



lamellar septa extending half way up the gill. Coecum of the crystal- 

 line style arising as a posterior continuation of the pylorus, large in 

 size, very curved and comparatively short in its course. Intestine 

 like that of Solen with an additional large loop before it ends in the 

 rectum. Heart posterior. The general conformation of the body 

 distinctly shows that the body has been elongated in its posterior 

 portion, perhaps beyond the posterior end of the visceral mass, 

 the remaining anterior portion being affected to a minimum. The 

 maximum of elongation has taken place in that portion of the 

 body which lies behind the posterior adductor muscle. 



Gen. Neosolen, gen. nov. 



1916. Soleii '! foiiesi, Annandale and Kemp, Mem. Ind. Mas. V , p. 



354. % 5. P'- ^vi, fig. 7. 

 1916. Solen ? foiiesi, Ghosh, ibid. p. 368, figs. 1-3. 



The present genus is erected for the reception of a species 

 which was doubtfull}^ thought to be a dwarfed form of Solen 

 fonesi, Dunker. The fairh^ complete literature at my disposal 

 shows that it ought to be referred to a genus of its own. I propose 

 for the species the name Neosolen aquae-dulcioris. The following 

 diagnosis is drawn from my anatomical notes (28) and from a 

 further examination of spirit specimens : — 



Animal. Body 3 to 3 J times as long as broad, sloping 

 anteriorly at both the anterior and posterior margins ; anterior 

 margin slightly curved. Pedal aperture confined to the anterior 

 margin and antero- ventral corner. Thick anterior margins of 

 the mantle lobes extending be^'ond the anterior margin of the 

 valves, Concresced ventral margins of the mantle lobes forming 

 a narrow surface. Siphon a long segmented piece, each segment 

 with a tentacular fringe round its distal margin. Anterior 

 adductor muscle elongated and narrow, with a short space 

 between it and the upper end of the pedal aperture. Posterior 

 adductor muscle oval, of smaller size than the retractor pedis 

 posterior muscle at its insertion. Foot elongated, cylindrical, 

 slightly flattened laterally ; it is stouter towards the apex, where 

 it forms a distinct rounded annular swelling and still further a 

 conical process at the tip. Fibres of the retractor pedis anterior 

 muscle passing between the longitudinal muscles and the pedal 

 cavity. Labial palps short and broad, subtrigonal, and about 

 one fourth the body length. Anterior lip immediately behind the 

 anterior adductor muscle, with no interval between the two. 

 Gills short and deep, 3^ to 4 times as long as broad and more than 

 half the body in length, just continued into the proximal portion 

 of the branchial canal ; visceral portion nearly as long as the 

 cloacal ; gills broadly plicate and sub-heterorhabdic, with inter- 

 plical junctions. Attachment of gills similar to those in Solen. 

 Coecum from the postero-ventral aspect of pjdorus and passing 

 forward in its long course. Heart pushed forward into the 

 anterior portion of the pericardial chamber by the outgrowths of 

 the kidneys which constrict the middle portion of the pericardium. 



