1856.] 91 



surface by undulation?. I think there was an ancient Tallev excavated in these 

 rocks before the period of the drift, that it was filled up during that period, and 

 that the river is now cleaning it out again." 



The bones referred to prove, on examination, to be those of the greater por- 

 tion of the hinder extremities of a young seal, but whether of a species distinct 

 from those now found living in the neighboring seas, is a question only to be 

 determined by careful comparison with the corresponding parts of the recent 

 animals. The soft distal extremities of the tibia and fibula are crushed together. 

 The bones of the ankle and foot are well preserved, but the epiphyses of the 

 latter are separated and only partially developed. The matrix in the vicinity of 

 the bones, is marked by the impressions of the hairs and skin which enveloped 

 them. 



Mr. Logan, in a report on the " Geological Survey of Canada," (1850, '51, p. 8,) 

 refers the deposit, in which the above described specimen was found, and simi- 

 lar deposits of the St. Lawrence and its tributaries, to the post-tertiary period ; 

 and he further observes, that in these deposits, ' the remains of whales, seals, 

 and two species of fishes, and many ma:ine shells of those species still inhabit- 

 ing the Gulf of St. Lawrence, are found ;" from which remarks, together with 

 those of Mr. Billings, and the appearance of the fossil itself, we are inclined to 

 suspect the seal of the Ottawa has its descendants yet sporting on the sea border 

 of the Canadas. 



Independent of all other considerations, the specimen is interesting, as ex- 

 hibiting the same process at the present geological period, which for so many 

 S'lccessive ages has preserved the remains of vegetables and animals, which are 

 now examined by the palaeontologist as so many iconographic illustrations of 

 life in the history of cur planet. 



Plate in. Representation, two-thirds the size of nature, of the greater por- 

 tion of the bones of the hinder extremities of a young seal, partially imb.dded 

 in one-half of a concretion of indurated claj', from a post-jiliocene deposit of the 

 Ottawa River, Canada. 



Notices of several genera of extinct Mammalia., previously less perfectly characterized. 



By Joseph Leidy, M. D. 



CARNIVORA. 



1. Delmctis, Leidy. 



Skull intermediate in form to that of Felis and Machairodus. Orbits more open 

 posteriorly than in either of these genera; and the anterior extremity of the 

 lower jaw constructed as in the latter. Formula of dentition as in Putorius, viz. 

 33 11 22 11 11 



in. c. p. m. car. m. tub. m. = 32. 



33 11 33 11 11 



Incisors relatively as well developed as in Felis, with the lower ones arranged 

 as in Putorius. Canines like those of Machairodus. First premolars small, those 

 succeeding robust with the upper pair bilobed, and the lower ones trilobed. 

 Carnassial molars like those of 3Iachairodus prima;vus. Lower tubercular molar 

 like that of Putorius ; the upper one thickest at its outer part. 



Deinictis felina, Leidy. Pr. A. N. S. vii, 127, 156. A unique species, with the 

 skull about the size of that of Machairodus primcevus, or about a fiifth smaller 

 than the Panther, (Felis concolor.) 



Locality. Mauvaises Terres of Nebraska. 



PACHYDERMATA. 



2. Hyracodon, Leidy. 



Skull without horns; with the cranium surmounted by a long and narrow 

 sagittal crest ; orbits better defined from the temporal fossae than in Rhinoceros ; 

 nasal bones articulating with the intermaxillaries, and deeply notched at their 



