42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I44 



lections (A.M. No. 2969) labeled "C. scottianus but a little larger," 

 and the hypocone is noticeably weaker. The hypocone, particularly 

 that of M2, is much weaker than in Cynodontomys knightensis. 



The New Fork jaw material referred to Cynodontomys scottianus 

 is comparatively robust and P4 relatively large, particularly in the 

 breadth of this tooth in two individuals. In comparison with Cyno- 

 dontomys knightensis, P3 is large but with an actually smaller talonid. 

 The trigonid portion of P4 appears more robust and with relatively 

 greater anteroposterior development than in the earlier species. The 

 metaconid is more posterior relative to the protoconid than is usual 

 in C. knightensis; moreover, the talonid of this tooth is highly varia- 

 ble and shows a cusp arrangement that does not so nearly conform 

 to that of the molars. The New Fork species is evidently much 

 smaller than Cynodontomys hmdeliusi White. 



CYNODONTOMYS, sp. 



The lower jaw from Knight Station (A.M. No. 12836), which 

 Granger considered as suggesting Lysite, has been labeled Cyno- 

 dontomys latidensf. As indicated in 1952, the absence of premolars 

 leaves some doubt as to the specific reference. Its size, however, is 

 about right for that species. 



TILLODONTIA 



ESTHONYCHIDAE 



ESTHONYX, cf. BISULCATUS Cope 



Isolated upper teeth of Esthonyx, which may be referred to E. bisul- 

 catus, were found by George Pipiringos at a locality just to the north 

 of Tipton Butte and much farther north at a lower level in the Knight 

 east of Steamboat Mountain, A lower molar, collected by our 1954 

 expedition from the lowest beds of the Knight exposed to the west 

 of Elk Mountain in the Fossil Basin, may also be of this species. 



ESTHONYX, cf. ACUTIDENS Cope 



(Plate I, figure 3) 



Two more isolated teeth from localities to the south of Big Piney 

 have been added to the materials representing the larger species of 

 Esthonyx in the La Barge fauna. 



