MEXICAN BOUNDAKY LINE. 163 



TURRITELLA, Lam. 

 TURRITELLA . 



Plate XIX, Figure 8. 



This figure represents a specimen of tertiary rock from San Diego^ California. Besides the 

 Turritella, which is not determined, there are a few small unknown bivalves. 



CASSIDULA, Humphreys. Sub-genus LACINIA, Con. 

 CASSIDULA ALVEATA. 



Plate XIX, Figure 9. 



Melongena cdveata, Con., Amer. Jour. Sci., vol. XXIII, p. 344. 

 Cassidula alveata, Con., Proc. Acad. Nat. Sci., vol. VII, p. 448. 

 Pyrula Smithii, Lea, Cont. to Geol., p. 153, pi. V, fig. 162. ^ 



Sub-globose, with revolving robust lines, and a wide, concave, revolving furrow below the 

 angle of the large volution ; spire very short ; suture deeply impressed, sub-canaliculate. 

 Locality. — Western Texas. 



