NO. 8 



MAMMALIAN FAUNA, BADWATER AREA — GAZIN 



19 



their relatively greater width, are more nearly symmetrical bilaterally, 

 exhibiting a slight crest forward from both the entoconid and meta- 

 conid, quite matching those of the labial side. 



As previously noted, there seems little doubt but that a phyletic 

 sequence is indicated from Helaletes through Desmatotherium to 



MEASUREMENTS IN MILLIMETERS OF UPPER DENTITIONS 



OF Desmatotherium woodi 



U.S.N.M. 



No. U.S.N.M. U.S.N.M. 

 20200 No. No. 

 Type 20201 20202 

 Length of upper premolar series, P'-P*, in- 

 clusive 33.3 



P\ anteroposterior diameter : greatest trans- 

 verse diameter 7.5 : 6.0 



P", anteroposterior diameter 8.3 : — 



P^ anteroposterior diameter : greatest trans- 

 verse diameter 9.0: 11.7 8.9: 11.8 



P*, anteroposterior diameter : greatest trans- 

 verse diameter 8.8:12.4 9.2:12.7 9.1:12.6 



Length of upper molar series, parallel to 



tooth row 37.5 



Ml, anteroposterior diameter perpendicular 



to anterior margin 11 .0 



Ml, transverse diameter across parastyle and 



protocone 14.0 



M«, anteroposterior diameter perpendicular 



to anterior margin 12.9 



M2, transverse diameter across parastyle and 



protocone 15.8 



M3, anteroposterior diameter perpendicular 



to anterior margin 13.7 



M3, transverse diameter across parastyle and 



protocone 15.6 



II.O 



13.8 



U.S.N.M. 



No. 



20204 



12.8 



15.0 



13-0 

 iS.i 



Colodon, and this may logically include Heptodon in the lower Eocene 

 which, in addition to a much reduced Pi, has only slightly less pro- 

 gressive premolars than Helaletes. The four genera are not readily 

 separated on the basis of molar teeth but a progressive change in the 

 premolars is noted, more precocious in tapiroid character than in con- 

 temporary isectolophodont and dilophodont forms (as well as hy- 

 rachyid). Nevertheless, this line evidently did not give rise to true 

 tapirs. 



