148 . UNIONIDvE. 



following measurements of four specimens in the Indian Museum 

 show: 



1. 2. 3. 4. 



Long 19 19 14 16-25 mm. 



Lat 33-5 31-25 22'5 23 mm. 



Diam 12 11-25 8-75 9-25 mm. 



Var. siliguriensis, Preston. 



Unio siliguriensis, Preston, Kec. Ind. Mus., Calcutta, ii, p. 47 (fig. 

 in text) ; op. cit. vii, p. 293, as N. (JR.) lima, var. siliguriensis. 



Original description : Shell inequilateral, ovate oblong, reddish 

 brown, sculptured with concentric lines of growth and oblique 

 transverse wrinkles, these latter being especially marked poste- 

 riorly ; anterior side rounded ; posterior side acuminately rounded ; 

 dorsal margin arched ; ventral margin very slightly contracted in 

 the middle ; umbones much eroded ; interior of shell iridescent, 

 pale bluish white. 



Long. 21, lat. 37'75 mm. 



Hdb. Siliguri, N. Bengal. 



Type in Indian Museum, Calcutta. 



Genus PHYSUNIO. 



Physunio, Simpson, Washington, D.C., Smiths. Inst., Nat. Mus. 

 Proc. xxii, 1900, p. 830. 



TYPE, Unio gravidus, Lea, from Siam, Cambodia, and Cochin 

 China. 



Range. Siam ; Cochin China ; Cambodia ; Sumatra ; Assam. 



Original description : Shell thin, irregularly obovate, narrowed 

 in front, decidedly produced at post base, pointed behind, and 

 posteriorly winged, with a moderate posterior ridge and often a 

 second or third faint ridge above it ; beak sculpture zigzag radial, 

 somewhat disposed in two sets, the one down the posterior ridge 

 slightly nodulous ; posterior slope having irregular radial corru- 

 gations, the rest of the shell smooth ; epidermis often cloth-like, 

 with one or more green rays on the posterior slope ; hinge-line 

 curved ; a single obliquely granularly striate pseudocardinal and 

 generally three laterals in the left valve, and two pseudocardinals 

 and two laterals in the right, all greatly compressed ; beak cavities 

 deep ; muscle scars irregular ; nacre bright, bluish, and iridescent. 



Animal unknown. 



Section LENS. 



Lens, Simpson, Washington, D.O., Smiths. Inst., Nat. Mus. Proc. 

 xxii, 1900, p. 831. 



TYPE, Unio eximms, Lea, from Siam and Cambodia. 



