Peterson: Material Discovered in Uinta Basin. 



81 



be as grciit a difference in the length of the face between A. robustiis 

 and A. nintense as appear in the original illustration and as stated by 

 Professor Osborn.^ 



This character together with the position of the orbit was until 

 very recently regarded by the present writer as possibly having 

 generic importance. A thorough review of the type of Achcenodon 

 robustiis reveals the fact that the specimen has received considerable 

 lateral crushing in the region of the frontals and anterior portions 

 of the parietals, which no doubt is at least a partial cause for the 

 apparently greater elongation of the cranium than in A. uintense: 

 When the orbit of the left side is carefully studied in relation to the 

 top of the skull it becomes plain that the characters in the type of 

 A. robustiis and the Carnegie Museum specimens of A. nintense 

 are almost identical; that is, the orbit is situated nearer the dorsal face 

 of the frontal than is the case in the illustration by Professor Osborn.^^ 

 This is corrected in PI. XXXIX, Fig. i of this paper. The end of the 

 muzzle in the Princeton specimen is, however, apparently heavier 

 than in A. nintense, which is possibly also partly due to crushing. 

 The chief points of difference between these species then are: the 

 much greater development of the posterior accessory tubercle of M- 

 the thicker premolars and the larger size of ^. nintense when compared 

 v/ith A. robustiis. (See illustrations of M^ PI., XXXIX, Figs. 2 

 and 4.) 



In skull No. 3182 the occiput is perfectly preserved and for the 

 first time gives us an accurate conception of this region. In Professor 

 Osborn's paper on A. nintense {I.e., p. 104) the occipital plate is repre- 

 sented as fan-like, while the specimen in the Carnegie Museum shows 

 that it has a more evenly rounded appearance from side to side (see 

 PI. XLVn, Fig. 3). 



Genus Parahyus Marsh. 

 21. Parahyus vagus Marsh. 



Amer. Jour. Sci., Vol. XII, 1876, p. 402; Amer. Jour Sci., Vol. XLVIII, 1894, p. 

 261. 



From casts of the types kindly communicated by the authorities of 

 the Peabody Museum of Natural History, it is possible to determine a 

 few significant characters, which may be regarded as possessing generic 



^"i.c, p. 103. 



^1 Contributions from The E. M. Museum of Geology and Archaeology of Prince^, 

 ton College. Bull. No. 3, 1883, pi. VI. 



6 DEC. 15, I919. 



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