ADDITIONAL OBSERVATIONS. 



The Lower Division embraces the vast Ferruginous 

 deposits of this country. Of its numerous fossils already 

 described, the following may be considered as uniformly 

 characteristic : Belemnites Americanus, Exogyra costata, 

 GryphsBa convexa, Ostrea Jalcata, Ammonites Dela- 

 warensis, Hamulus onyx. &c. &c. which are distributed 

 from New Jersey to Arkansas. This division also em- 

 braces the remains of Saurians and Fishes, (p. 27.) 



II. 



I have received, through Dr. Mantell, a note from 

 M. Agassiz, in reference to the teeth of Fishes figured on 

 Plates XI. and XII. of this work. M. Agassiz observes, 

 that so far as he can decide from the drawings, these re- 

 mains may be identified as follows : 



PI. XI. Fig. 6. Galeus pristodontus. 

 " Fig. 11. Lamna acuminata. 



" Fig. 4. Mantelli. 



u Fig. 1. — obliqua. 



" Fig. 5. lanceolata. 



" Fig. 2 and 3. Lamna plicata. 

 PI. XII. Fig. 3 and 5. Carcharias lanceolatus. 

 " Fig. 4. Carcharias megalotis. 

 " Fig. 2. polygurus. 



Mr. Mantell adds the highly interesting facts, that of 

 these species, the Galeus pristodontus, Lamna acuminata 

 and Lamna Mantelli, are also found in the chalk of Eng- 

 gland 5 that the Saurocephalus lanciformis and S. Leanus 



