TERTIARY PERIOD. 



521 



of Ruminants; Titanotherium, Elotherium, Rhinoceros, Mastodon, Choeropotamus, 

 Leptochcerus, of Multungulates ; Chalicomys, Ischyromys, Palseolagus, Eumys, of 

 Rodents. 



Dr. Evans states with regard to a jaw of the Titanotherium Proutii seen by 

 him, that it had a length along the range of the teeth of five feet ; and that one 

 skeleton, as it lay imbedded, measured eighteen feet in length and nine feet in 

 height. 



E. Yorktow.v Epoch.— 1. Mollusks. —Fig. 819, Crepidula costata ; fig. 820, 

 inside view of the same; fig. 821, Yoldia limatula Say, also recent; fig. 822, 



Gasteropod.— Figs. 819, 820, Crepidula costata. Conchifers.— Fig. 821, Yoldia limatula; 

 822, Callista Sayana. 



Callista Sayana ; Pecten decennarius ; P. Virginianns ; Cardium Yirginianum ; 

 Mercenaria tridaenoides • M. capax ; Chama corticosa ; Axincea Tumulus; Ano- 

 mia Rufjfini ; also, among living species, Ostrea Virginica, or common Oyster; 

 Venus mercenaria, or common Clam (recently referred to the new genus Mercena- 

 ria, and named Mercenaria violacea) ; Venus cancellata Mactra 3fulinia lateralis; 

 Pecten concentricus ; Lunatia Heros ; Oliva litterata ; Nassa Tritia trivittata, etc. 



2. Vertebrates. — (a.) Fishes. — Carcharodon megalodon ; Galeocerdo latidens 

 Ag. ; Hemipristis SerraAg.; Oxyrhina hastalis Ag. — (6.) Mammals. — Balsena 

 prisca Leidy; B. p>n^seatlantica L. ; Delphinus Conradi L. ; Phoca Wymani 

 L., etc. 



In the Miocene of Oregon, on the Columbia, there are numerous fossils, in- 

 cluding remains of Cetaceans, Fishes, Crustaceans (Callianassa Oregonensis 

 Dana), and nearly fifty species of Mollusks. None of the latter are of living 

 species: Xucula divaricata Con. closely resembles N. Cobholdise Sowerby, of the 

 English Miocene; Lucina acutilineata Con. can scarcely be distinguished from 

 the recent Atlantic coast species L. contracta Say, and Lunatia saxea Con. is 

 as nearly related to Lunatia Heros. (Conrad.) 



In the Miocene of Ocoya Creek, California, occur teeth of Sharks of the genera 

 Echinorhinus, Scymnus, Galeocerdo, Prionodon, Hemipristis, Carcharodon, Oxy* 

 rhina, and Lamna, besides a tooth of a Zygobates, (Agassiz.) 



