204 



tab. 8, fig. 1 a, ?>,) from which it is distinguished by its unequal valves, 

 greater proportional width, and smaller muscular scars. 



Lower Cretaceous, head of Pine Cr. Lamar County. 



Dr. G. G. Shumard collector. 



Genus Cyprina, Lamarck. 



C. Laphami, (n. sp.) Shell small, subtriangular, longer than 

 wide, broad anteriorly and cuneate behind; umbonial region very 

 gibbous ; posterior slope falling abruptly to the margin, and almost 

 perpendicular to the sides; buccal side short, narrowly rounded; 

 anal side long, truncate at extremity, declining in a very gentle curve 

 from beak to posterior end ; pallial margin gently convex ; beaks 

 near the anterior margin, elevated, incurved, pointed. 



There are a number of specimens of this species before me, but 

 the substance of the shell in all of them has been changed into pul- 

 verulent chalk, which does not preserve any of the surface markings. 



Length, 0.40 inch; width, 0.32; thickness, 0.27. 



Resembles C. Saussuri (Brong. sp.), but is a much smaller species. 



Bluffs of Red River, Fannin County. Named in honor of I. A. 

 Lapham, Esq., of Milwaukie, Wisconsin. 



Dr. G. G. Shumard collector. 



Genus Lucina, Bruguiere. 



L. parvilineata, (n. sp.) Shell broadly ovate or subcircular, a 

 little longer than wide, compressed ; valves very gently convex ; 

 buccal, pallial, and anal margins rounded and forming a continuous 

 curve ; anterior cardinal margin longer than the posterior and gently 

 arcuate ; beaks small, moderately elevated, directed backwards and 

 situated nearest the anterior end. Surface marked with closely 

 crowded, concentric striae, and obscure radiating lines on the anterior 

 and posterior slopes. 



Length, 0.74; width, 0.70; thickness, 0.26. We have seen but 

 one example of this very neat species . It was found in the Ripley 

 Group, near Corsicana, Navarro County. 



S. B. Buckley collector. 



Genus Anatina, Lamarck. 



A. SULCATINA, (n. sp.) Shell large, ovate, thin, inequivalve, very 

 inequilateral ; . length not quite equal to the width ; anterior end 

 broadly rounded ; posterior end short, contracted, narrowly rounded ; 

 pallial margin gently convex ; beaks small, but little elevated, situated 

 posterior to the middle ; cardinal margin straight, or very slightly 

 convex before the beaks, and very slightly arched behind ; a narrow, 

 distinctly im})ressed and very gradually expanding sulcus, extending 

 from beak to palUal margin, which it cuts a little behind the middle ; 



