R. S. Lull — Fauna of the Dallas Sand Pits. 165 



Dentition. — The dental formula was probably that of 

 Antilocapra: I J, Cj, Pf, Mf =32 teeth. The cheek teeth 

 are hypsodont, with prominent external styles, no trace 

 of cing-ula nor of internal basal pillars. Crowns of the 

 premolars curved backward as in Antilocapra. Com- 

 pared with those of Antilocapra, the chief distinctions 

 lie first in the relative size of the teeth, M^ being approx- 

 imately equal in each form. The other molars of Tetra- 

 meryx are progressively larger than in the prongbuck, 

 while the premolars are progressively smaller. In 

 Tetrameryx the mesostyle is more pronounced on M^, 

 while in the premolars the external styles are much less 

 conspicuous. On the other hand, IVP in Antilocapra 

 bears a distinct hypocone which is lacking in Tetrameryx. 

 The degree of hypsodonty is about the same. 



Measurements. 



Tetrameryx Antilocapra 



No. 1.50, No. 0180, 



S. M. U. Y. P. M. 



mm. Eatio mm. 



Length, premolar-molar series 76 1.05 72 



P^-P* 25 0.89 28 



]VP- M^ 52 1.099 47.5 



P2, length 6.7 0.87 7.6 



P*, height of crown 14 1.03 13.5 



Length 8 0.89 9 



M\ length 13.3 1.02 13 



M2, length 17.5 1.16 15 



M^ length 21.4 1.20 17.8 



Extreme height of tooth to apex of 



fang 46 1.12 41 



Average ratio 1.03 



Palate. — The palate, in so far as preserved, corre- 

 sponds to that in the prongbuck, except that in the latter 

 the anterior margin of the posterior nares does not 

 extend forward of the after limit of the dental series. 

 In the fossil it extends to a point opposite the middle of 

 M^. It also seems to have had a more acute forward 

 angle. The palatal foramen is about opposite the for- 

 ward margin of M^ in the two old prongbucks before me, 

 while in two juvenile specimens it lies further forward; 

 that of the fossil lies between the two. The position of 

 the infraorbital foramen can not be compared. 



