SCOTT : LITOPTERNA OF THE SANTA CRUZ BEDS. 45 



no peculiarities of pattern are visible. That the animal was a female, is 

 perhaps indicated by the very thin lower tusk. 



In L. floweri the cranium is not known. The facial region (PI. VIII, 

 fig. i) is short and of remarkable dorso-ventral depth ; taking the length 

 of the upper dentition as loo, this depth, measured from the alveolar 

 border of m- upward, is 59.3, while in Diadiaphorus niajusculus this pro- 

 portion is only 43.6, being actually as well as relatively less in the latter. 

 The skull, with the mandible, must have had something of the same 

 square, heavy outline in side view as is found in Hyracodon. The frontal 

 sinus and antrum together form a large, convex surface in front of and 

 above the orbit. The nasals are broad and strongly convex from side to 

 side ; their full length is not preserved, but the portion remaining is 

 actually longer, and therefore proportionately much longer, than in Dia- 

 diapJionis majusctdtts ; they also differ from the latter in having an articu- 

 lation with the premaxillae, which appears to be relatively shorter than in 

 Proterotherhmi, and the rounded, depressed alveolar sheath of the tusk- 

 incisor is also shorter than in some species of the latter. As in all of the 

 Santa Cruz members of the family, the palatine processes of the premaxillae 

 are small, those of the maxillaries extending forward between the very 

 broad ascending rami of the former to the incisive foramina. The anterior 

 narial opening is high and narrow, with moderate backward inclination, 

 and the posterior opening is very far back, with front border between the 

 second molars. 



All of the mandibles are unfortunately incomplete, lacking the angle, 

 coronoid and condyle. The horizontal ramus is notably stout, thick in 

 all parts and very deep dorso-ventrally in the posterior part, where the 

 alveolar border and tooth-row curve upward ; anteriorly the ramus becomes 

 shallower and the symphysial region is procumbent. 



Associated with this skull fragment are the two thoracic vertebrae pre- 

 viously described, the astragalus, calcaneum and third metatarsal. Except 

 for their smaller size and slightly more slender proportions, these bones 

 display hardly any tangible difference from those of DiadiapJiorus majus- 

 cidus, except that the proximal part of mt. Ill is distinctly more com- 

 pressed planto-dorsally and that the plantar surface is broader than in the 

 latter. 



