354 



Memoirs of the Indian Museum. 



[Vol. V, 



?*&:■>•*:>&#*#■'• 



kind, which Mr. Preston has called 5. annandalei and S. kempi occur in the outer 

 channel of the lake and at Nalbano, while a third (S. ? fonesi) which is relatively 

 shorter than either, is one of the most abundant species of Lamellibranchs in the 

 main area. Shells of the two former are found together and both would seem to bur- 

 row only in sandy ground, whereas the third is essentially an inhabitant of soft mud. 

 5. annandalei and S. kempi are comparatively scarce and, with the exception of a 

 single small specimen of the latter, are represented in our collection by dead shells 

 only. Dr. Ekendranath Ghosh describes the general structure of 5. ? fonesi in con- 

 siderable detail in the appendix on pp. 367-374. 



? Solen fonesi, Dunker, Preston, 1916, p. 37; syn. 5. truncatus, Preston, 1914, 



p. 309. Plate xvi, fig. 7. 

 In his paper of 1914 Mr. Preston regarded this shell as a young form of S.trun- 

 catus, Wood, which it resembles in outline. Many sexually mature individuals were, 

 however, found that were no larger than those examined by him. 



We obtained in the Chilka Lake no shell more than 28-5 mm. long and, in a series 

 of specimens that we have measured, we find that the length varies from 3+ to a little 

 more than 3J times the breadth. 



Von Martens 1 , who regards 5. fonesi as synonymous with 5. woodwardi, Dunker, 



notes that Dunker' s speci- 

 mens were from 51 to 53 

 mm. long and 11 to 12 mm. 

 broad ; Reeve's figure is 

 59 mm. long and 12 mm. 

 broad. Von Martens con- 

 cludes that small specimens 

 are about 4 \ times as long 

 as broad, and larger ones 

 as much as 5 times. If 

 Mr. Preston's identification 

 is correct, the Chilka race 

 is evidently a dwarfed one. 

 The question of propor- 

 tions in this and closely 

 allied species is, however, 

 one of great difficulty. 

 Three valves found on a 

 sandy beach at the mouth 

 of the Ennur backwater near Madras and identified by Mr. Preston as 5. fonesi, are 

 respectively about 86, 72 and 71 mm. long. The first of these is 5f times as long as 

 broad and the other two about 4J times — -measurements and proportions that do not 

 by any means tally with those given by von Martens. 



;+,^^^'-i,'-,..^7i^ r.'^^-W/rTw 



ct. 



6. 



Fig. 5. — Chilka race of Solen ? fonesi, Dunker. 



a. A living specimen, slightly enlarged, with extruded foot and 



siphon. 



b. A portion of the siphon, more highly magnified, lateral view. 



c. A cast-off section of the siphon, end view. 



Weber's Zool. Ergebn. Nied. Ost.-Ind., IV, p. 279 (1897). 



