10 H. Dofc. 129. 



MYTILUS, Lin. 



7. M. HUMERUS, Con., pi. 1, fig. 10. Ovate, ventricose, summit 

 acute ; anterior margin rectilinear ; basal margin rounded ; anterior 

 extremity obtusely rounded ; posterior extremity less obtuse ; disk 

 with minute radiating lines. 



Locality. Canada de las Uvas, with the preceding fossils. 



CARDITA, Brug. 



8. c. PLANICOSTA, pi. 1, fig. 6. Obliquely cordate ; ribs about 22, 

 broad and flattened, separated by a narrow groove which becomes ob- 

 solete towards the base ; ribs on the posterior slope narrow, indistinct, 

 and crossed by numerous profound wrinkles. Lunule small, cordate, 

 profoundly impressed ; inner margin crenate. 



Locality. Canada de las Uvas, with the preceding fossils. Veneri- 

 cardia planicosta Lam. An. Sans Vert. (Desh. ed.) vol. vi., p. 381. 



This common species occurs much larger, though less perfect, than 

 the one represented. This shell occurs abundantly in the Eocene 

 strata of Maryland, Virginia and Alabama, and is quite as charac- 

 teristic of the American as of the European Eocene period. I dis- 

 covered it in Maryland in 1829, and at that time regarded it as the 

 first indication of the occurrence of deposits in the United States syn- 

 chronous with those of the London clay. Prof. Kogers has since 

 named this shell Venericardia ascia. 



NATICA, Jdanson. 



9. N. (ETITES? Con., pi. 1, fig. 7. 



Locality. Canada de las Uvas, with the preceding fossils. 



N. cetites, Conrad. Foss. shells of Tert. Form. October, 1833. 



10. N. GIBBOSA and SEMILTJNATA, Lea. cont. to Geol., December, 1833. 

 There is but one specimen of this shell, which I refer with doubt to a 

 Claiborne species. The outline is similar to that of the latter, but 

 the aperture is concealed in the rock, which prevents the necessary 

 comparison to determine the identity or the difference. 



2 N. ALVEATA, Con., pi. 1, fig. 8 and 8a. Volutions 5, flattened 

 above, carinated on the angle, a few minute obsolete lines revolve on 

 the upper side of the whorls ; aperture inclining to an obovate form ; 

 umbilicus small. 



Locality. Canada de las Uvas. 



This species is remarkable for its truncated whorls, which are chan- 

 nelled by the carina on the margin. There are no analogous species 

 in the Eocene of the Atlantic slope. 



TURRITELLA, Lam. 



11. T. UVASANA, Con., pi. 1, fig. 12. Subulate, whorls with the 

 sides straight and oblique above, rounded below, and having large 

 revolving striae with intermediate minute lines ; strife near the suture 

 on the upper part of the whorls finer than the prominent lines below. 



Locality. Occurs with the preceding, in Canada de las Uvas. 



