38 



ON THE EXTINCT MAMMALIA OF 



t( 





Antero-posterior diameter of lower sectorial molar, 

 Height of do., ..... 



Antero-posterior diameter of first lower tubercular molar, 

 « " second " " 



upper sectorial molar, 

 " first tubercular molar, 

 Transverse diameter of " " " " 



Distance from incisive alveoli to back of the latter tooth, 

 Breadth of face between the canine alveoli, 



" " " sectorial molar alveoli. 



Distance from sagittal crest to end of nasal bones, 

 Breadth of forehead at post-orbital processes, 

 Length of forehead, .... 



Length of nasal bones, .... 



RY^NODONTIDM. 



HYJENODON. 



Eycenodon is a remarkable extinct genus of carnivora, apparently the type of a 

 family no longer in existence, partaking of characters of the Wolves, Cats, Hyaena, 

 Weasels, and the smaller plantigrade animals, besides exhibiting resemblances to 

 some of the carnivorous marsupials. 



The genus was first indicated under the name of Hycenodon by MM. de Laizer and 

 de Parieu, from a lower jaw with teeth, discovered in the inferior miocene formation 

 of Auvergne, Puy-de-Dome, France. Remains, apparently of another species, found 

 in association with those of Palceotherium and Aiioplotherium, in the gypsum quarries 

 of Montmartre, near Paris, had been described by Cuvier, who recognized their 

 eminently carnivorous character, and, from the prolongation of the palate, considered 

 them as belonging to an animal allied to the Raccoon, Badger, Coati and the 

 Mangusta. 



Altogether about five species of Hyce^wdon have been indicated from the tertiary 

 formations of France, of which the best characterized, H. leptorhyncliits and H. hra- 

 chyrhynchus, were derived from the lower miocene, and the others belong to the 

 upper eocene deposits. 



The remains of three distinct species of the same genus have been discovered in the 

 Mauvaises Terres of White River, Dakota, by Dr. John Evans, Dr. Benjamin 

 Shumard, Dr. Hayden and Mr. Meek. 



