210 FROCEEDINGS OF THE NATIONAL MUSEUM. 



expanded posteriori}^, but to nothing like the extent seen in the 

 Mesonychidse or Marsupialia. The lachrymals have a broad semi- 

 circular expansion upon the face, but the foramen is completely within 

 the orbit. This condition appears to be generallj^ characteristic of the 

 Creodonta. In true Carnivora the lachrymal has a very slight expanse 

 on the face, the maxillar}" coming nearly or quite to the margin of the 

 orbit. In the carnivorous marsupials there is some expansion of tho 

 lachrymal upon the face, but in this group, as in the Insectivora, the 

 lachrymal foramen is more or less external to the orbit. A much 

 closer approach is seen among the Ungulata, where the lachrymal has 

 a very large facial expansion, the foramen entirely intra-orbital, and 

 the tubercle on the margin of the orbit. The form and extent of the 

 facial part of the lachrymal approaches that in Sinopa most nearly 

 in the primitive types — Oreodon, Dacrytherium, Agriochoerus, Hyra- 

 chyus, etc. In the more elongate skulls of later Ungulates it becomes 

 much more expanded. 



The facial expansion of the lachrymal appears to be correlated with 

 the position of the orbits, which in Sinopa.^ as generally among the 

 Creodonta, are farther back than in modern Carnivora. In Sinopa 

 they lie above M--; in Cauls the}' are above P--M^; in Yi'verra above 

 P^-M^; in the opossum above M^"^. In Ungulata they are above or 

 behind the molars, and the extension of the lachrymal on the face 

 varies in accordance. 



The frontals are short, extending back on the top of the skull only 

 to the posterior part of the temporal crests and forming no portion of 

 the sagittal crest. At the sides they extend but slight!}- farther back, 

 to the postorbital constriction, which is immediately behind the ante- 

 rior end of the sagittal crest. They are broad anteriorly and inflated 

 above the orbits, leaving a marked depression along the median line, 

 deepest in front of the sagittal crest and shallowing out as it approaches 

 the posterior margin of the nasals. 



The parietals are remarkably long, extending well down on the sides 

 of the skull and including the whole of the sagittal crest. 



The premaxillaries are large, with wide ascending portions and 

 moderately large infraorbital foramen situate above P-; the muzzle in 

 front of this is compressed and deep; behind this pointthe skull expands 

 rapidly as in Daphaenus and the Canidse generally. 



The jugal is of moderate size and rather long; its anterior branch 

 extends under the orbit and has a considerable contact on the face 

 with the lachrymal, thus excluding the maxilla from any near approach 

 to the orbit; the inferior branch is short, the posterior branch extends 

 backward lieneath the zygomatic process of the squamosal nearly to 

 the glenoid fossa, ending in a slender splint, as among the Carnivora 

 generally. In the opossum its posterior end is thickened and forms a 

 considerable part of the anterior side of the glenoid fossa, while a 



