﻿262 NEPHRONAIAS 



iiieiis of this species in the National Museum collection from 

 Nicarag:ua without s[)ccilie(l locality. The type of orcgonen- 

 sis is somewhat larger than von Martens' specimen, but there 

 are shells that almost exactly agree with his in size and form. 

 The ra\ s are not shown anything like so clearly in Lea's figure 

 as they slicmld be. 



Nepiiron.mas ciiAMPioNi ( vou Martcns). 



Shell small, compressed oblong elliptical, densely inequally 

 striate, subsolid, with a moderate, somewhat double posterior 

 ridge ending in a slight hiangulation behind ; beaks slightly 

 elevated, placed rather near the anterior end, their sculpture 

 not observed , epidermis fuscous, pale and obscurely radiate in 

 the region of the beaks ; pseudocardinals subcompressed ; 

 nacre bluish. 



The small shell figured is probabl}' a young female, as it 

 is rather full at the post-basal region. 



Length 30, height 17, diam. 6.5 mm. 



West Guatemala; I'aso Antonio, in the Pacific coast region. 

 Unio charnpioni von Martens, Biol. Cent. Am., Moll, 1900, 



p. 508, 1)1. XXXVIII, figs. 9, 9a. 



I cannot tell much about this species as the description is 

 in Latin and the figure is not very clear. I rather incline to 

 believe it an immature female Nephronaias, and it would seem 

 to be near oregoncnsis or macnielii, but from the description 

 it appears to be more strongly sulcate than either. 



Nephronaias rowei.lii (Lea). 



Shell subtriangular or subelliptical, pointed behind and 

 bluntly pointed in front ; dorsal and basal lines curved, the 

 dorsal more strongly so ; posterior ridge well developed, round- 

 ed or sometimes faintly and narrowly biangulate ; beaks rather 

 high, moderately full, their sculpture consisting of fine, doubly 

 looped ridges, which are often slightly nodulous at the bases 

 of the loops; surface somewhat concentrically sulcate; epi- 

 dermis olive, feebly rayed in the young shells ; left valve with 



