﻿I.AMPSII.IS 195 



SPECIKS INCERT.^ SliDTS. 



Lamtsilis MOCTEZUMENSis Pilsbrv. 



"The shell is oblong-, the dorsal and ventral margins both 

 arched, the former a little more so : altitude decidedly more 

 than half the length, diameter more than one-third the length ; 

 moderately strong, but not thick. The beaks are small and low, 

 near the anterior fourth of the length. In young shells they 

 show one or two low, short undulations, being nearly smooth. 

 Color yellowish-brown. Adult shells hardly showing rays, even 

 by transmitted light, but the young have narrow green rays 

 posteriorly, on a yellow ground, marked with dark concentric 

 streaks. Both ends are rounded. Sculpture of growth-wrin- 

 kles only, weak on the middle of the valve, but rather emphatic 

 anteriorly. The interior is white, the nacre thinner and iri- 

 descent posteriorly. The pseudocardinal teeth are moderately 

 stout, blunt and nearly smooth. In the left valve the posterior 

 cardinal is larger than the anterior. In the right valve the 

 single cardinal is small. The lateral teeth are short and widely 

 separated from the cardinals. The cavity of the beaks are 

 rather deep. 



Length 68, height 38.5, diam. 24 mm." (Pilsbry.) 



Type locality. Moctezuma River, State of San Luis Potosi, 

 Mexico. 

 Lampsilis nwctccnmcnsis Pilsbry, Pr. Ac. N. Sci. Phila., iQoq. 



p. 534, pi. XXV. figs. I, 2, 3, 4. 



"This species has some resemblance to spatulatiis (Lea). It 

 differs from the related species by wanting corrugations on the 

 posterior slope." 



Lampsilis novileonis Pilsbry. 



"The shell is oblong, rather compressed, the upper and basal 

 margins slightly and about equally arcuate, anterior end round- 

 ed, posterior end sloping above, truncate and somewhat bian- 

 gular below, beaks at the anterior two-sevenths of the length. 

 The surface is convex, without angle or ridge bounding the 

 posterior slope, not very glossy, smoothish for the greater part, 



