No. 7.] NIMRAVID^ AND CANID^E OF THE MIOCENE PERIOD. 179 



Temnogyon Cope. 



Paleontological Bulletin, No. 30, p. 6, December 3, 1878 ; Proceedings Ameri- 

 can Philosophical Society, 1878, p. 68. 



Dental formula : I. ^ ; C. j- ; Pm. ^ ; M. f . Two molars in each jaw 

 tubercular. Inferior sectorial with well-developed heel, which is keeled 

 with a cutting edge above. An internal tubercle of the same. A post- 

 glenoid, but no postparietal foramen. Humerus with an epitrochlear 

 arterial foramen. 



The characters on which I rely at present for the discrimination of 

 this genus from Canis are two. The first is the presence of a cutting 

 edge on the superior face of the heel of the inferior sectorial, in place of 

 a double row of tubercles surrounding a basin. When well developed, 

 these characters present a broad contrast, but indications of transitional 

 forms are not wanting. Thus, in some extinct Canes the internal crest 

 of the heel is less elevated than the external, which is the homologue 

 of the single crest of Temnocyon, and in some specimens of Temnocyon 

 corypliwus there is a cingulum on the inner side of the median keel, 

 which represents the internal crest of Canis. Secondly, the epitrochlear 

 foramen of the humerus, a character common to all of our Lower 

 Miocene Canidce yet known. 



The keel of the sectorial, which defines this genus, is simply a repeti- 

 tion on that tooth of the heel which belongs to the posterior premolar 

 teeth of many Carnivora. It finds resemblances in such Eocene forms 

 as Mesonyx and Palceonyctis. Among recent Canidce it is apparently 

 unknown, and is very rare in other groups. The Cynodictis crassiros- 

 tris Filhol, from the French Phosphorites, strongly resembles the species 

 of Temnocyon in generic characters. 



Three species of the genus are known to me. They may be distin- 

 guished as follows. A fourth species, T. josephi, is provisionally placed 

 with these : 



I. First superior tubercular molar with a wide median fossa, bounded within by a 



tubercle. 

 Length of superior molar series from canine, .070 ; of true molars, .0215. 



T. altigenis. 

 Length of molar series from canine, .067 ; of true molars, .014. 



T. rvallovianus sp. nov. 



II. First superior tubercular molar with narrower basin, bounded within by a V-shaped 



crest. 



Length of dental series from canine, .055 ; of true molars, .014 T. coryplmua. 



Length of dental series from canine, .051 ; of true molars, .013 ; muzzle narrow, 



zygomas wide T. josepld sp. nov. 



All of the above species have been derived from the Truckee Miocene 

 beds of Oregon. I, however, anticipate the discoverj^ of these or other 

 species of the genus in the White Eiver beds of Dakota and Colorado. 



