330 THE PUERCO FAUNA. 



The second individual includes part of the superior walls of the skull. 

 The fragment displays a high sagittal crest, which is fissured in front so as 

 to keep the temporal ridges ai)art to near its anterior ai)ex. The brain sur- 

 faces show small, smooth. Hat hemispheres, separated by a constriction fi< (in 

 the wide and large olfactory lobes. The navicular bone shows three well- 

 defined distal facets, indicating probably five digits in the pes. The teeth 

 of this specimen include a posterior superior molar, and an infericM- thinl or 

 fourth premolar, with other teeth. The premolar is like that of a creodont. 

 Its principal cusp is a simple cone. To this is added a short wide heel, 

 whose superior surface is in two parts, a higher and a lower, divided by a 

 median ridge. A low anterior l)asal lobe, and a weak external cinguUun 



The third specimen belonged to an individual a little smaller than the 

 other two. It includes the first inferior true molar, a titoth lust from the 

 others. Its form is somewhat narrowed anteriorly, where it has two lnw, 

 but well separated anterior inner tubercles, which form a V with the exterpal 

 anterior. 



Specimen No. 1 is accompanied by fragments of vertebrae and limbs. 

 The former are principally from the lumbar region, but fragments of the 

 atlas remain. This vertebra is of moderate length, and the cutylus is some- 

 what oblique. The vertebrarterial canal is rather elongate, and its anterior 

 groove-like continuation in front of the diapophysis is not deeply excavated. 

 The lumbar vertebra? are remarkable in the characters of their zygapo[)hyses. 

 These display subcylindric surfaces of the posterior pair, which indicates 

 that the anterior ones are involuted, as in the specialized Artiodactyles and 

 Perissodactyles of the later geological ages. Such a structure does not 

 exist among carnivora, nor in any mannnals of the Lower Eocene, to my 

 knowledge, excepting some creodonta. I do not find it in Dklelphys nor 

 Phascolarctos, but it exists in a moderately developed degree in Sarcophilus. 

 It is, however, entirely similar to the airangement in Mesonyx obtusidens, which 

 see. The articular surface forms more than half of a cylinder, and its sujte- 

 rior portion is bounded within by an anteroposterior open groove. The 

 surface within this is not revolute, as in Bos and Su~s, but the articular sur- 

 face disaj)pears, as in Cervus. Eight such postzygajiophyses are preserved, 

 all disconnected from their centra. Two of them are united together. There 



