DICOl Vl.l.v.K. OF AMERH v. '.V.\'.) 



the first premolar is trilateral, with one principal lobe, and has its basal ridge open ex- 

 ternally. The last superior true molar of the cave head is trilateral, with its rounded 

 apex posterior, while in Platygonus it is broader, quadrate, has its constituent portions of 

 the basal ridge laterally less developed, and has its postero-external lobe better developed. 



Having said enough to prove the cave head is not only specifically but generically dis- 

 tinct from Platygonus compressus, we have next to compare it with the specimens referred 

 to Dicotvles depressifrons. With this purpose in view, the first thing which strikes us in 

 examining the fragment of skull of the latter is the evident existence of the acute ridge on 

 the side of the superior maxillary bone, proceeding from the inferior margin of the malar 

 bone, as in recent species of Dicotvles, but which does not exist in the cave head. 



In the fragment of the skull of Dicotvles depressifrons, as before stated, the forehead 

 appears to have been longer than broad, as in recent species of the genus, but in the cave 

 head the breadth greatly exceeds the length. 



The face is very much broader in Dicotvles depressifrons than in the latter, and has 

 probably been -diorter, for in the fragmenl the distance from the: upper end of the inter- 

 maxillaries to the suture of the nasal process of the superior maxillary bones with the 

 frontal is a little over two inches, while in the cave head from the same points the distance 

 is one and a quarter inches greater. 



In Dicotvles depressifrons the nasal process of the upper maxillary bone is broader and 

 more rapidly divergent anteriorly than in the cave head. The upper extremity of the 

 intermaxillaries in the former incline 35°, while in the latter it is nearly vertical, and the 

 face behind these bones, -till sloping in the Dicotyles depressifrons to the margin of the 

 maxillo-malar r i 1 1 lt < ■ , is vertical in the cave head until it begins to dilate posteriorly. 



Other but more trifling dilferences exist, but it is evident, from the comparison which has 

 been made, that the cave head, without doubt distinct from Dicotyles, also evidently could 

 not have belonged to the same animal characterized by the cranial fragment as Dicotyles 

 depressifrons. 



The only specimen among those referred to Protochccrus prismaticus sufficiently cha- 

 racteristic for comparison with the cave bead is the fragment of a last upper molar. The 

 first upper true molar of the cave head has about the same size, and if worn down to the 

 same extenl would probably have the same appearance as that ascribed to Protochcerus, 

 which, however, would also be the case with the much worn tooth of Dicotyles. The 

 lower canine also of the cave head, if much worn down, would present about the same 

 size and proportions as that of Protochcerus, and this also would be the case with that of 

 the collared Peccary under the same circumstances. 



The la-t upper molar of the cave head is in a trilling degree broader than that of Pro- 

 tochcerus, and the postero-external lobe is relatively to the others less developed. The 

 basal ridge in the former posteriorly forms three short tubercles, enclosing as many foveas, 

 but in the lra'_ r ment of tooth in the same position forms a prominent lobe, larger than the 

 filth lobe of the la-t lower molar of the cave head, and to the antero-extcrnal side of this 

 lorn, ler and -mailer tubercle, the two enclosing a single fovea. 



These charai b r ol comparison which have been presented between the corresp mding 



