DESCRIPTION OF THE PLATES. Xlil 
Tas. XXXI. 
. A tooth of the Ptychodus decurrens. 
. A tooth of the Ptychodus Oweni. 
. A tooth of the Ptychodus latissimus. 
. A tooth of the Ptychodus mammillaris. 
. A tooth of the Ptychodus rugosus. 
6 & 7. A tooth of the Ptychodus Mortoni. 
8. Squaloid vertebra, probably of Ptychodus. 
9. A tooth of the Ptychodus depressus. 
10 & 10a. Teeth of the Ptychodus polygyrus. 
11. A tooth of the Enchodus halocyon. 
12. Portions of jaws of Saurocephalus lanciformis. 
13 & 13a. Two views of a tooth of Oxyrhina crassidens. 
14. Fin-rays of a Ptychodus. 
15. A portion of fossil shagreen, or skin of a Placoid fish. 
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16. Vertebrz of Tetrapterus minor. 
17. Two views of a tooth of Otodus appendiculatus. 
18 & 184, 6. Tooth of the Lamna acuminata. 
19. Vertebra of Placoid fish. 
20. Tooth of a Mosasauroid reptile. 
21 & 21a. Tooth of a Leiodon, two views. 
Tas. XXXII. 
Figs. 1 & 2. Upper maxillary bone, left side, of Edaphodon Mantelli. 
3 & 4. Mandible of Orthagoriscus. 
5. Teeth of Ptychodus decurrens. 
6 & 6*. Dental plate of Aulodus Agassizu. 
7. Microdon nuchalis. 
8. A group of teeth of Gyrodus conicus. 
9. Two teeth of Acrodus Illingworthi. 
10. Coelorhynchus cretaceus. 
11 & 12. Calamopleurus Anglicus. 
Tas. XXXII*. 
Fig. 1. Portion of rostrum or prolonged premaxillary bone of Saurocephalus lanciformis. 
2. Microdon occipitalis. 
3 & 3*. Prionolepis angustus. 
4. Dental plate of Plethodus oblongus. 
5 & 5*. Teeth of a new species of Microdon. 
6 & 6*. Teeth of a new species of Gyrodus ? 
