440 EXTINCT MAMMALIA OF NORTH AMERICA. 



ONTOCETUS. 

 Ontocetus £iuiiionsi. 



Leidy: Proc. Ac. Nat. So. 18.59, 162. Emmons: Man. Gcol. Phila. 1860, 219, with Fig. of a 

 tooth half the natural size. Cope : Proc. Ac. Nat. Sc. 1867, 144. 



Indicated by a mutilated tooth remarkable for its shape and size. It is curved 

 conical, laterally compressed and fluted. In its perfect condition it has been upwards 

 of ten inches in length by about four inches in its greater diameter from before back- 

 ward and two and a half inches transversely. It is composed of dentine with an 

 exterior comparatively thin layer of cementum, and an interior comparatively large 

 amount of osteo-dentine. The lower extremity of the fang is solid. The specimen 

 is eroded in several positions, apparently as if the detached tooth had lain some time 

 at the bottom of the sea, exposed to the boring action of some molluscous or other 

 animal. 



The specimen, half the size of nature, is represented on page 219, of Emmons' 

 Manual of Geology, published in Philadelphia in 1860. It was obtained from the 

 miocene formation of North Carolina, but the exact locality is not mentioned by Prof. 

 Emmons. The relations of the animal to which the specimen belonged are uncer- 

 tain. It may have pertained to a cetacean like the Sperm Whale; perhaps to a 

 Walrus-like animal. 



HEMICAULODON. 



Hemicaulodon effodiens. 



Cope : Proc. Am. Phil. Soc. 1869, 191, PL V, Fig. 6. 



Of the same uncertain reference as the specimen indicated in the preceding notice 

 of Ontocetus, is the fragment of a tooth, from Monmouth Co., New Jersey, desci'ibed 

 by Prof. Cope under the above name, and suspected by him to belong to a sirenian. 



BAL^NID^. 



BAL^NA. 



Baleena mysticetoides. 



Emmons : Rep. North Carolina Geol. Surv. 1858, 204, 205, Fig. 26. 



Founded on an otolite from the miocene of North Carolina. 



PROTOBALiENA. 

 Protobalsena palaeatlautica. 



Balmna palwatlantica, Leidy : Proc. Ac. Nat. Sc. 1851, 308 ; Auc. Fauna Neb. 1853, 8. Cope : 



Proc. Ac. Nat. Sc. 1867, 132, 144, 147. 

 Balcmojttcra j^aheathmtica, Cope : Proc. Ac. Nat Sc. 1868, 192, 193. 



Founded on a jaw fragment, accompanied by several vertebras, from the miocene 

 formation of City Point, Virginia. The form and construction of the portion of 



