﻿chambp:ri,ainia 219 



Genus CHAMBERLAINIA Simpson, 1900. 



Charnberlainia Simpson, Syn.. iqoo, p. 582. 



Shell large, very solid in front, thinner behind, round or 

 round obovate, with low posterior ridge, alate on the post- 

 dorsal part when young ; beaks full, sculpture not seen : sur- 

 face without sculpture excepting a few slightly pustulous cor- 

 rugations on the posterior slope ; epidermis dull, not rayed ; 

 hinge curved ; pseudocardinals rather small, stumpy, two in 

 the left valve and one in the right ; laterals short, remote, the 

 intervening hinge plate rounded, one lateral in the right valve 

 and two in the left, the upper the smaller, and all curved up- 

 ward along their inner edges ; beak cavities not deep ; dorsal 

 muscle scars numerous, deep, extending from the cavity down- 

 ward and forward ; area outside the pallial line very wide ; 

 nacre lurid bronzy. Animal unknown. 



Type, Unio hainesianus Lea. 



ClIAMBIiRLAINIA HAINESIANA (Lea). 



Shell short obovate, solid, subcompressed^ with moderately 

 high, subcompressed beaks, from which a rounded posterior 

 ridge runs out a short distance on to the disk and vanishes ; 

 there is a very small anterior and a moderate posterior wing, 

 which is corrugately plicate ; a slight radial sinus runs from 

 the beaks to the posterior part of the shell just above the 

 median lines; epidermis warm brown, rather dull; left valve 

 with two small, erect pseudocardinals and two remote laterals, 

 the upper the smaller, both having the inner edges reflexed ; 

 right valve probably having one pseudocardinal and one lat- 

 eral ; beak cavities moderately deep, with a row of scars under 

 the pseudocardinals ; anterior muscle scars rough, impressed ; 

 posterior scars shallow ; nacre white and very thick at the an- 

 terior base, the rest lurid, somewhat iridescent behind ; pallial 

 line a long way from the border of the shell. 



Length 203, height 150, diam. 78 mm. 



Siam. 



