164 J. B. Hatcher — Recent and Fossil Tapirs. 



base of the nasals, where it attains a depth of 8 mm , and a 

 width at the top of 12 mm . The premaxillaries in the present 

 specimen are broken off at the base of the canines ; they were 

 strong, and had an extended contact with the maxillaries. 



The most striking differences between the skull of Prota- 

 pirus and that of the recent Tapirs are to be seen in the con- 

 formation of the superior aspect of the skull, and in the posi- 

 tion of the f rontals and nasals, relative to the other elements of 

 the skull. In Protapirus the top of the skull, from the tip of 

 the nasals to the occipital crest, is a nearly straight line, while 

 in most recent Tapirs it is somewhat convex, and in T. terrestris 

 (Americanus) it is strongly convex, especially in the region of 

 the parietals and frontals. In the characters just mentioned 

 T. roulini, among modern Tapirs, is most like Protapirus. 

 In recent Tapirs the nasals occupy a position considerably pos- 

 terior to that of the nasals in Protapirus, in which the 

 posterior border of the nasal opening is directly above the 

 anterior border of the orbit ; while in recent Tapirs it is always 

 back of the posterior constriction of the orbit. 



The nasals are slightly injured in the present specimen, and 

 it is impossible to determine their exact length, they could 

 hardly have reached much in front of the posterior border of 

 the premaxillaries ; they are applied closely to each other, but 

 are not coossified. They are narrow, deep, and triangular in 

 cross-section anteriorly, but gradually expand and present a 

 greatly thickened lateral edge, posteriorly. On the upper sur- 

 face, and a little in front of the middle of the nasals, there is 

 a ridge, running from the inner margin obliquely forward to 

 the outer, and giving to these bones a peculiar twisted appear- 

 ance. The frontals are low and broad, with distinct postorbital 

 processes ; from which temporal ridges extend obliquely back- 

 ward and inward and unite to form a low, sharp, sagittal crest. 

 The -lateral edges of the frontals, above the orbits, are thickened 

 and bent upward so as to form the external wall of the groove 

 above described. The fronto-parietal suture marks the point 

 of greatest constriction in the temporal fossa. The parietals 

 are moderately expanded, and unite superiorly in a low, sharp, 

 sagittal crest ; which becomes broader in the region of the 

 supra-occipitals, and gradually expands into the occipital crest, 

 which is deeply emarginate, and considerably overhangs the 

 occipital condyles. The combined length of the parietals and 

 frontals in Protapirus is considerably greater than that of the 

 same bones in Tapirus indicus or Elasmognathus bairdii, the 

 two largest species of recent Tapirs, notwithstanding that 

 skulls of either of the latter are fully two-thirds longer than 

 the skull of Protapirus ; from this comparison the remarkable 

 reduction of the length of those bones, in modern Tapirs, 

 becomes apparent. 



