52 Annals of the Carnegie Museum. 



the tooth is but very little greater than that of P4. There is a slight 

 cingulum on the external face of the trigonid, but internally the tooth 

 is smooth, except the cingulum of the heel just described. Mg- is 

 much reduced in size and in this respect suggests the condition in 

 Procynodictis and Cynodictis rather than in Daphcenus and Daphce- 

 nodon. The trigonid of this tooth is, however, lower than in the illus- 

 tration given of Procynodictis and suggests more nearly that found in 

 later forms (Cynodictis); the heel is slightly basin-shaped. M3- was a 

 small one-rooted tooth which in the type is represented only by the 

 alveolus. 



Except the mandible just described, the humerus, minus the proximal 

 end, is the only part of the type worthy of description. The shaft is 

 quite heavy and rather long, and the deltoid ridge is robust and ex- 

 tends downwards more than half the length of the shaft, terminating 

 abruptly, which plainly furnishes the cynoid characters given by 

 Matthew & Wortman. The ulnar border of the distal end of the 

 shaft is not complete, but enough is preserved to show that the supi- 

 nator ridge was ciuite prominent and extends well up, in this respect 

 being unlike the supinator ridge of Mimocyon longipes, which is much 

 less extended upwardly and more like w^hat is found in most species of 

 Miacis and of Lycarion {Vulpaviis) hargeri. The distal trochlea, 

 though broad, is not as broad in proportion as in Mimocyon, and the 

 middle portion of the articulation for the radius is much less convex 

 and more nearly approaches what is seen in the genera of later for- 

 mations {Daphcenus and Daphamodon). The entepicondyle and the 

 radial border of the entepicondylar foramen is broken off. There 

 was apparently no supra-trochlear perforation. 



Measurements. 



Length of mandible, canine to M3 approximately 65 mm. 



Depth of mandible, canine to P2 approximately 22 



Transverse diameter of mandible at symphysis opposite Pj 10 



Length of molar-premolar series approximately 58 



Length of premolar series approximately 36 



Length of molar series approximately 23 



Genus Pleurocyon gen. nov. 

 6. Pleurocyon magnus sp. nov. (Plate XXXV). 



Type: Symphysis of lower jaws with left ramus nearly complete 

 and a portion of the dentition in place, C. INI. No. 2928. 



