150 GEOLOGY AND PALEONTOLOGY. 



CAEDIUM (PROTOCAEDIA) TEXANUM. 



Plate VI, Figuee 6, a, h, c. 

 Cardium ERlanum, Koemer, (not Sowerby,) Kreide. von Texas, p. 39, pi. VI, fig. 12. 

 Cordate, subquadrate, obliquely truncated posteriorly; umbo sligbtly oblique, submedial; 

 disk concentrically ribbed ; ribs large and prominent, rounded, laterally abrupt, fine and close 

 on tbe umbo ; post-umbonal area with about IT tuberculated radiating lines. 

 Locality. — Between El Paso and Frontera. 



CARDIUM (PROTOCAEDIA) FILOSUM. 



Plate VI, Figure 7, a, h. 

 Triangular, elevated, with numerous minute, concentric lines anterior to the umbonal slope, 

 which is obtusely carinated ; umbonal and post-umbonal slopes marked with close, fine radii, 

 about 30 in number. 



This is the smallest species I have seen, and the only one with a carinated umbonal slope. 

 Locality. — Leon Springs. 



CARDITA, Lam. Blainville. 



CAEDITA EMINULA. 



Plate VI, Figure 8. 



Ovate-acute from beak to base, elevated ; ribs 16, prominent, rounded? Those on the anterior 

 slope angular, acute, umbo narrow, beaks pointed and elevated. 



There is one specimen of this — a cast of both valves ; there appear to be traces of radiating 

 lines between the ribs. 



Locality. — Leon Springs. 



CORBULA. 



CORBULA OCCIDENTALIS. 



Plate VI, Figure 9. 

 Allied to C. oniscus, Con.; but has finer and more numerous concentric furrows. It is pro- 

 bably an Eocene species ; but was found in western Texas. 



NEITHEA, Drouet. 



This o-enus, it appears to me, should be restricted to that group of shells with an angular 

 base of which Pecten quinquecostatus, Sowerby, is the type. So restricted, the genus is probably 

 confined to the Cretaceous strata, and is certainly highly characteristic. No species of it occurs 

 in Tertiary formations, nor in a living state. 



NEITHEA OCCIDENTALIS. 



Plate V, Figure 1, a, b. 



Neitheaoccidentalis. Conrad. Proc. Acad. Nat. Sci. vol. VII, p. 269. 



Pecten quadricostatus, Eoemer, (not Sowerby,) Kreide. von Texas, p. 64, pi. VIII, fig. 4. 



Ovate-triangular ; lower valve inflated^ unequally ribbed, and concentrically striated, lines 

 very fine ; large ribs rounded and elevated, smaller ribs equal, two in number in each of the 



