THE MAMMALIA OF THE DEEP RIVER BEDS. 



63 



and it would be much to the advantage of clearness and consistency if the White 

 River were called Oligocene, a view for which Cope has long contended. 



In the descriptive portion of this paper the fossils will be treated according to 

 their systematic position, as the interest attaching to them is especially morphologi- 

 cal. The lack of smaller animals in the collections is very noticeable. The lower 

 beds have yielded but one rodent and the upper none at all ; only two carnivores, 

 both dogs, have been found. None of the Insectivora or Chiroptera have been 

 detected. The fauna, as so far known, consists, therefore, almost entirely of medium 

 and large-sized ungulates, for which the conditions of fossilization are, no doubt, 

 chiefly responsible. 



CARNIVORA. 



CsmidaB. 



CYNODESMUS Scott. 



(PI. I, Figs. 1-5.) 

 Amer. Naturalist, 1893, p. 6G0. 



Canine animals having the dentition of the microdont forms of Cams, but with 

 the skull structure of the ancient genera. Cerebral hemispheres small, not overlap- 

 ping the olfactory lobes or cerebellum, and with fewer and simpler convolutions than 

 any of the recent Canidm. Postglenoid foramen concealed or absent. 



Ctnodesmus thooides Scott. 



(loc. cit.) 



Dentition microdont ; deuterocone of upper sectorial relatively well developed ; 

 face short, cranium elongate ; small frontal sinuses present ; mandible non-lobate 

 with stout angular hook and broad, recurved coronoid ; size medium. 



The technical distinction of this genus from Cynodictis is by no means easy, 

 and yet it becomes very clear on an examination of the two ; while the latter very 

 probably represents a side branch, leading away from the direct canine phylum, the 

 former may, with equal probability, be regarded as being either in the direct line of 

 canine descent or but little removed from it. 



In order to make clear the character of this interesting form, it will be most 

 convenient to compare it carefully with some typical modern species, for which pur- 

 pose the coyote, Canis latrans, will be taken as a standard. 



I. Dentition". A. Upper Jaw, The incisors are very small and form a nearly 

 straight row, the external pair projecting but little behind the others. The first and 



A. p. S. — VOL. XVIII. L 



