EXPLANATION OF THE PLATES. 
PLATE I. . PLATE III. 
Fig. 1. Belemnites Americanus, Fig. 1. Terebratula Harlani, 
2. Transverse section of the same 2. ‘Terebratula fragilis, 
fossil, 3, 4. Terebratula Sayi, 
3. Same, subfusiform, 5. Ostrea falcata, 
3-a. Variety of the same species ? 6. Ostrea panda, 
- Obscurely chambered, and ob- 7. Turritella encrinoides, 
tuse at the apex, 9. Ostrea plumosa, 
4, Belemnites? ambiguus, 10. Scalaria annulata, 
5. Transverse section magnified, 11. Arca rostellata, 
6. Baculites ovatus, 12. Clypeaster florealis, 
7. Transverse section of the same, 13. Turritella vertebroides, 
8. Same species, 14, Cassidulus sequoreus, 
9,10. Anthophyllum atlanticum, 15. Nucleolites crucifer, 
11. Patella tentorium, 16. Spine of Echinus, 
12. Baculites asper, 17. Plate of do. 
13. Transverse section, 18. Young of Spatangus parastatus, 
14, Vermetus rotula. 19. Ananchytes cinctus, 
20. Ananchytes fimbriatus, 
PLATE II. 21. Spatangus parastatus, full grown. 
Fig. 1. Ammonites placenta, from a 
specimen fifteen inches in PLATE IV. 
diameter, Fig. 1, 2. Gryphea convexa, 
2. Septa, natural size, 3. mutabilis. 
3. Ammonites Vanuxemi, 
4, Marginal view of the same, PLATE V. 
5. Ammonites Delawarensis, Fig. 1. Cytherea excavata, 
6. Scaphites reniformis, 2. Plagiostoma pelagicum, 
7. Ammonites telifer, 3. Tornatella bullata, 
8. Hamulus onyx. 4. Pecten anatipes, 
