I I 66 l.AMKI.r.lDF.NS 



Post-dorsal winsr low or wanting. 



Shell oval, rather solid, L. jenkinsioint.s. 

 Elliptical or subrhomboid. 



Solid smoky brown, L. consobrimts. 



Siibsolid, shininq-, often banded. L. marginalis; 

 cancfrianns; thwctitesii; corrianus. 



Thin. dark. L. lamellatus. 



Lonq- rhomboid, black, L. scntitm. 



Cuneate, L. narainporcnsis. 



Elongate ovate, L. nongyangcnsis; phenchooganjensis. 



Su])genus Lamki.i.tdkns s. s. 

 Shell dark colored ; teeth well developed. 



J^AMELLIDENS MARGiNAUS (Lamarck). 



Shell subrhomboid or subelliptical, thin or subsolid, convex, 

 inequilateral ; beaks but slightly inflated, not greatly elevated, 

 their sculpture consisting of subradial curved bars, the inner 

 of which coalesce below ; sometimes the bars are slightly zig- 

 zag; surface nearly smooth; posterior ridge rounded, ending 

 in a blunt point on or below the median line ; epidermis usually 

 polished, sometimes showing faint wrinkles arranged in radial 

 series, brownish or yellowish-brown, marked with one or more 

 yellowish-tawny or straw-colored concentric bands ; on the 

 dorsal slope there are two elevated, radial threads and often 

 faint, greenish rays : teeth delicate and lamellar, pseudocardi- 

 nals two in each valve, placed opjiosite each other in the right ; 

 anterior and posterior muscle scars shallow, nacre bluish to 

 salmon, generally soft and brilliant. 



Length 85, height 45, diam. 26 mm. 



Length no, height 56, diam. 35 mm. 



India; Burma; Pegu; Ceylon; Canton River, China? I 

 believe that Monsson's U. crancsccns is L. marginalis. but can 

 it be from Java ? 

 Die breite Mahler-Miischcl ans Grbnland, Schroter, Flussc, 



1779, p. 181, pi. IX, fig. I. 



? Unio iira-iilandica Morch, Am. Jl. Conch.. IV, 1868, p. 38. 



