TERTIARY PERIOD. 



521 



of Ruminants; Tit another him, Elotlterium, Rhinoceros, Mastodon, Cheer opotamus, 

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

 Rodents. 



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

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

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

 height. 



E. Yorktown 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 

 822, Callista Sayana. 



821, Yoldia limatula; 



Callista Sayana ; Pecten decennarius ; P. Virginianus ; Cardium Virginianum ; 

 Venus difformis ; V. capax ; Chama corticosa ; Axinsea Tumulus; Anomia 

 Ruffini; also, among living species, Ostrea Virginica, or common Oyster; Ve- 

 nus mercenaria, or common Clam (recently referred to a new genus, Uercenaria, 

 and named Mercenaria violacea) ; V. cancellata ; Mactra lateralis ; Pecten con- 

 centricus; Lunatia Heros ; Oliva litterata ; Nassa trivittata, etc. 



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



Ag. ; Hemipristis Serra Ag.; Oxyrhina hastalis Ag. — (&.) 3fammals. — Balsena 

 jjrisca Leidy ; B. palseatlantica 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 : Nucula 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, Hemip>ristis, Carcharodon, Oxy- 

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



