NO. 7 MAMMALIA FROM THE ALMY FORMATION — GAZIN 9 



Claenodon line. The result of this is a broadening of the basin of the 

 talonid giving it a rather different appearance than, for example, in 

 Cluenodon montanensis. Nevertheless, the lovi^er molars have retained 

 clear definition of the principal cusps, showing the Claenodon pattern, 

 which is nearly lost in the crenulate character of the more flattened 

 tooth crowns of Eocene Anacodon. 



The character of the anterior portion of the jaw in Aiiacodon? 

 nexus cannot be determined, nevertheless the reduction of the anterior 

 premolars, the development of a diastema behind the canine, and a 

 flange on the lower jaw below the symphysis characteristic of Ana- 

 codon has already been anticipated in Claenodon acrogenius of the 

 lower Tiffanian in the Bison Basin, However, in C. acrogenius the 

 flange is comparatively incipient and the lower canine is enlarged 

 rather than reduced. Moreover, the lower molars of C. acrogenius, 

 except for size, would appear to be indistinguishable from those in 

 other species of Claenodon. I suspect that the anterior portion of the 

 lower jaw of Anacodon? nexus was deepened and exhibited a di- 

 astema behind the canine, although this is not certain, and there 

 remains the possibility that A.? nexus is a survival of more typical 

 Claenodon with shallow symphysis and unreduced premolars, but 

 with the tooth pattern advancing parallel to that leading to Anacodon. 



Ml in No. 21282 of Anacodon? nexus measures approximately 

 9.5 mm. in length by 7.8 mm. across the talonid. Mo is about 10.7 mm. 

 long and 8.5 mm. across the trigonid. 



MESONYCHIDAE 



DISSACUS, sp. 



The upper tooth portion (U.S.N.M. No. 16699) including the pro- 

 tocone and metacone, previously (Gazin, 1942) listed as a "creodont, 

 gen. and sp. undet.," may well be an anterior molar of Dissacus. A 

 second tooth fragment, the posterior portion of a lower premolar, 

 possibly P2 or P3, also suggests Dissacus. These are evidently of a 

 form not greatly different in size from the Torrejonian Dissacus 

 navajovius, clearly smaller than Dissacus praenuntius Matthew of 

 the Clark Fork beds. 



MIACIDAE 



DIDYMICTIS?, sp. 



A left Ml may well belong to a species of Didymictis, but is very 

 much smaller than contemporary Didymictis protenus proteus from 



