1919-] N. Annandale : Bombay Streams Fauna. 15T 



The measurements of four specimens are as follows : — 

 lycngth. Height. Thickness. 



1 • • 44 mm. 25\5 mm. 18-4 mm. 



2 .. 35-1 mm 21 mm. I3"2 mm. 



3 .. 22*5 mm. i3"6 mm. 9'4 mm. 



4 .. 172 mm. 10 mm. 6-9 mm. 



Type-specimen. — No. M 1 1398/2 in the register of the Zoologi- 

 cal Survey of India [Indian Museum). 



Locality. — Yenna River, Upper Kistna watershed, at Medha; 

 common, with P. corrugata, in the pool in which Limnocnida indica 

 occurs. 



Parrcyssia corrugata (Miiller). 



This species is even commoner in the Yenna River at Medha 

 than the former one. The shells, which are much eroded, vary 

 greatly in shape, some being much broader and less tumid than 

 others. The external sculpture is always strongly but irregularly 

 developed. The colour of the periostracum is dull brownish or 

 greenish, and the nacre has a strong salmon pink tinge. 



The measurements of three specimens from Medha are as 

 follows : — 



Genus Lamcllidens, Simpson. 



This genus is represented in the collection by two varieties of 

 the commonest Indian species, L. marginalis. 



Lamellidens marginalis (Lamarck) 



There is a single small valve of this species, in rather bad 

 condition, from the Medha River. 



Lamellidens marginalis var. cylindrica (H. and T.). 

 (Plate IV, fig- 5). 



1876. (Unio marginalis var. cylindrica, Hanley and Theobald, Couch, 

 /lid., p. 20, pi. xliv, fig. I. 



We assign to this variety with some doubt a series of shells 

 from the Igatpuri reservoir in the Nasik district (alt. 2,000 feet). 

 On the whole they resemble the figure in the Conch, Ind., but are 

 considerably smaller and have the anterior margin less broadly 

 rounded and the posterior dorsal margin a little more elevated. 

 The shell-substance has a distinct salmon-pink tinge and the epi- 

 dermal membrane is translucent olivaceous with obsolescent dark 

 radiating lines. The outline is very like that of L. mainwaringii, 

 Preston, but the valves are much more inflated, there are differ- 



