NO. 7 MAMMALIA FROM THE ALMY FORMATION GAZIN I3 



ECTOCION, cf. OSBORNIANUM (Cope), 1882 



A right lower jaw fragment with P4-M2 (U.S.N.M. No. 20645) 

 has teeth more robust than in the jaw belonging to the E. ralstonensis 

 skull, and in addition P4 is more progressive with a better developed 

 talonid basin and a large entoconid. P4, moreover, has a rather dis- 

 tinctly developed paraconid or parastylid. This specimen is tentatively 

 regarded as representing the Gray Bull species E. oshornianum. There 

 are in addition three other jaw fragments, each with a comparatively 

 large molar which may likewise be referred. 



Although Granger (1915) recognized three species of Ectocion in 

 the Clark Fork beds, including both E. ralstonensis and E. oshorn- 

 ianum, Simpson (1937b), in his treatment of the material, believed 

 (except for rare E. parvus) that a single species was represented in 

 which there w-as a shift in the mean size, the length of Mi for ex- 

 ample, between successive horizons from Clark Fork to Lost Cabin 

 time. While this seems evident in the demonstration given, I am, 

 nevertheless, concerned about the more progressive P4 in the larger 

 Almy specimen. The character of P4 might likewise show marked 

 variation within a species, but there are three small-toothed or 

 E. ralstonensis specimens which have P4 preserved, and in each of these 

 this tooth is distinctly less progressive. The correlation may be a 

 coincidence, but if not, I am inclined to believe that in this instance 

 a distinct species is actually represented. 



MEASUREMENTS IN MILLIMETERS OF TEETH IN THE SPECIMEN OF 



Ectocion, cf. osbornianum, u.s.n.m. no. 20645 



P4, anteroposterior diameter : transverse diameter of talonid 7.5 : 5.1 



Ml, anteroposterior diameter : transverse diameter of trigonid 6.8 : 5.9 



M2, anteroposterior diameter : transverse diameter of trigonid 7.1 : 6.5 



PHENACODUS ALMIENSIS Gazin, 1942 



Plate 2, figures 3 and 4 



A relatively small species of Phenacodus, P. ahniensis, is clearly 

 the most abundantly represented form in the fauna. The 32 speci- 

 mens in the collection referred to it comprise about 44 percent of the 

 total. The type specimen, U.S.N.M. No. 16691, consists of maxillae 

 wnth the canines and P^ to M^ in a scarcely worn state, together with 

 certain limb and vertebral portions. Although collected in 194 1, it 

 remains after six subsequent collecting trips the best specimen of this 

 species extant. 



