XI. TAXONOMIC STUDIES ON THE SOFT 

 PARTS OF THE SOIvENIDAE. 



By Ekendranath Ghosh, M.Sc, M.D., Offg. Professor 

 of Biology, Medical College, Calcutta. 



(Plates II, III.) 



Introduction. 



The anatomy of nearly all the known genera of Solenidae has 

 been described by Bloomer (5-17) in a series of papers published 

 in the Journal of Malacology , and in the Proceedings of the Malaco- 

 logical Society. The animal of Solen sloanii, Gray, has been briefly 

 described by Hedley (31) in 1899. Drew (25), in the year 1907, 

 noted the anatomy of Ensis directus, Conrad, along with its habits 

 and especially its movements. In the year 1916, Annandale and 

 Kemp {Mem. Ind. Mus. V, p. 354) added a short note on what was 

 then doubtfully considered to be a dwarfed form of Solen fonesi, 

 Dunker, and I described the anatomy (28) in an appendix to the 

 same paper. No stress has been put upon the taxonomic impor- 

 tance of the soft parts, however, in any of these publications with 

 the exception of a single one of them titled '' Classification of the 

 British species of the genus Solen, Linne " by Bloomer (5) and 

 scattered notes in his other papers. The present paper aims at 

 treating the subject with a view to define the subfamilies and 

 genera from the soft parts, including their gross internal anatomy. 

 It is also intended to append an account of the gross anatomy of 

 species, the soft parts of which are still unknown. 



I should specially mention that I have received all the speci- 

 mens from the Zoological Survey'' of India through the kindness of 

 Dr. N. Annandale. Lastly, I heartily thank Prof. H. H. Bloomer 

 for his kindness in sending his papers to me at my request. 



Generai, Notes on the Soft Parts. 



The animals are either narrow and elongated with more or 

 less straight and parallel margins or short and broad (deep) with 

 rounded margins. 



Mantle IvObES. The mantle lobes are fused with each other 

 in various degrees in the different genera. The fusion, being 

 incomplete, has left a number of gaps bounded laterally b}^ free 

 mantle margins and described as apertures. An anterior aperture 

 for the protrusion of the foot is formed by the separation of the 

 anterior margins of the mantle lobes. This is known as the pedal 



