92 BULLETIN OF THE 



APHELOPS, Cope. 



The generic characters of Ajihi-lojin have been given by Cope as follows. Den- 

 tition, 1. -J-, C. T, P. -3-, M. §; post-glenoid aiul post-t\ niiianic processes 

 in contact but not co-ossilied ; digits, 3-13 ; nasals hornless. To tliese cliarac- 

 ters may be added : niagiiuiu nut supjiorling Ulnar anteriorly; absence of the 

 'crista' and invariable presence of tlie more or less strongly developed ' crochet ' 

 and ' antici'ochet ' in the superior molars. 



The specific nomenclature of Aphdops is in confusion. The type oi A. (Rlii- 

 noccrun) cruasus, Leidy,^ is a last u]>per molar, which is closely siniilui- to that of 

 A. majaloduii ; the characters of the milk molar associated with this type cannot 

 be used in definition.'^ The penultimate upper molar, the type of A. mcridl- 

 anus, Lei-ly,* corresponds in the developmenl of the two 'crochets' to the same 

 tooth in A.fossigcr, Cope, but the posterior ' fossette ' is not ench)sed by the strong 

 cingulum as in the latter species. A. (^Aceralhcriuvi) acutum, Marsh, is identical 

 with A. fossigcr. A. 'innluorhinn!;. Cope, resumbles A. mi:ridianus in tlie open 

 posteri(;r fossette and llie dcNclojimi'iit of the ' ci-Drhcts.' It is inijK.issililc, how- 

 ever, to ch'ar up tiiis synnn^in}' without bringing the original types togetlier 

 for conipari.son. General characteristics ot all the.-e types are the invaiialde 

 development of the 'crochet,' absence of the 'cri>ta,' usual development of the 

 'anticrocliet.' The specific names propo.sed by Cope are here ado]>ted because 

 they are established upon a very complete linov.iedge of the skull as well as 

 of the teeth. 



Aphelops fossiger, CorE. 



Dentition : I. ^, C. 5, P- f > ^I- §• First premolar siin[)le, conical, sometimes 

 absent ; nasals not overhanging premaxillaries ; foramen lacerum medium 

 confluent with foramen ovale ; occiput broad and L)W ; limbs short and bulky ; 

 molars with well developed 'crochet' and 'anticrochet.' 



Ill the figure given by Marsh (Am. Jonrn. Sci., Oct., 1887, p. 3) and by Cope 

 (Am. Nat., Dec, 1879, p. 771 f)> ^''^ third and Iburth premolars have both the 

 'crochet ' and 'anticrochet.' There is some ground for the supposition that the 

 sknll here described belongs to a different species, since the 'anticrochet' is not 

 developed in the premolars. This reference is therefore provisional. 



This is apparently the only species Avhich is represented in this ci^Ilectiou. 

 All the specimens are from Kansas, and include several skulls and well pre- 

 served bones from all jiarts of the skeleton, enabling us to give a complete 

 description and restoration of the animal. 



1 See Ext. Man^m. Fauna, Dak , p. 228. 



2 Cope has nevertlieless employed the ' cristae ' developed in this milk molar in 

 his definition ni A. crnssiis. "On the Extinct Species of llhinoceriid£e of North 

 America," etc., liulL U. S. Geol. Survey, Vol. V. No. 2, p. 237. 



