374 E. L. Troxell — Entelodonts in Marsh Collection. 



In comparing with the type of A. clavus clavus, a sim- 

 ilarity prevails in size and in a few generalities, but it dif- 

 fers in many details of structure and in the more massive 

 proportions; the dependent process from the jugal is 

 nearly a half broader; the posterior process is heavy, 

 curves downward and its flattened end actually forms a 

 part of the glenoid cavity (cf. Dinohyus) . The anterior 

 process from the temporal is deep and has a sigmoid 

 curve on its lower border; the frontals are folded and 

 grooved, very rugose over the orbits and wide anteriorly, 

 and the lachrymals are correspondingly narrow. The 

 anterior mental tubercle is not compressed, but is rounded 

 and heavy at the end ; the posterior tubercles are long and 

 slender ; a larger diastema exists before and also behind 

 P 2 . P 4 is wider than long. The teeth are in general 

 heavier, smoother, and possess less of cingula and talon ; 

 especially the premolars are shorter and wider, except 

 that the posterior heels are laterally compressed. 



Following are shown the ratios of the two type speci- 

 mens at hand, compared to the type of A. mortoni Leidy. 



* 



o 



s 





•8 





© 





ft |S 



.2 



3 



1 



Q |3 



.2 

 P3 



5> 



o | ft 

 .2 



mm. 



% 



mm. 



% 



mm. 



% 



89.0 



74.7 



66.5 



71.2 



63.4 



95.3 



15.7 



78.3 



12.3 



70.1 



11.0 



89.4 



31.7 



86.7 



27.5 



91.5 



29.0 



105.4 



12.6 



119.0 



15.0 



121.4 



15.3 



102.0- 



19.0 



95.8 



18.2 



110.5 



21.0 



115.3 



22.2 



98.2 



21.8 



94.6 



21.0 



96.3 



63.5 



83.4 



53.0 



78.7 



50.0 



94.3 



76.2 



81.4 



62.0 



78.3 



59.7 



96.3 



Height of nasal suture above 



alveolus of P 3 



Breadth of nasal at same place 

 Ant.-post. diameter of P 3 at base 

 Transverse diameter of P 3 at base 

 Ant.-post. diameter of P 4 at base 

 Transverse diameter of P 4 at base 

 Height of face from middle 



nasal suture to palate 



Same height at P 4 



* Measurements taken from Leidy 's type description and reduced from 

 inches to millimeters. 



The great range in the ratios between the types of A. 

 mortoni Leidy and A. clavus Marsh is sufficient to sepa- 

 rate the two species. The incompleteness of Leidy 's 

 type, however, makes it almost impossible to compare 

 other specimens with it and to work out the finer distinc- 

 tions between the species. The main differences are : the 

 relatively greater antero-posterior diameter of P 4 in the 



