EDENTATA OF THE SANTA CRUZ BEDS. 27 1 



summit a short and sharp vertical ridge, with a small but deep pit on each 

 side of it ; the condyles are rather small and are separated ventrally by a 

 deep and narrow notch ; the foramen magnum is a vertical oval and the 

 paroccipital processes are quite long ; the basioccipital is broad, unkeeled, 

 and anteriorly is nearly plane, becoming strongly convex behind, where a 

 deep depression is formed on each side between the condyle, tympanic 

 and paroccipital process. The mastoid portion of the periotic, which is 

 quite extensively exposed, lies in a deep fossa between the squamosal and 

 exoccipital. 



Owing to the shallowness of the postorbital constriction, the frontals 

 have less of the hour-glass shape than those of Hapalops, and much more 

 prominent sagittal crest and temporal ridges ; the forehead is nearly plane 

 longitudinally, slightly convex transversely, the sinuses not causing any 

 external protuberances ; the anterior border has two shallow emarginations 

 for the nasals, without distinct nasal processes. As compared with those 

 of Hapalops, the nasals are short, very broad and moderately arched both 

 longitudinally and transversely ; at the anterior end they are somewhat 

 broadened and decurved to follow the maxillaries ; another and a very 

 marked difference from the last named genus is to be seen in the anterior 

 ends of the nasals, which are not deeply notched, but abruptly truncate 

 and, consequently, have no lateral processes. 



The premaxillae (Plate LVI, fig. 2), are of the same general plan as 

 those of Hapalops, but have nevertheless quite a different appearance ; 

 they are very short and are lodged in so deep a notch of the bony palate 

 that they project very little in front of the caniniform teeth ; the anterior 

 branch is very short, rather slender, and contracts rapidly forward ; on the 

 other hand, the poste'ro-external branch is very broad, much broader than 

 in any known species of Hapalops and the spine is narrower, though quite 

 heavy ; the incisive foramen is thus reduced to a narrow oval, considerably 

 smaller than in Hapalops, but much larger than the narrow slit of Hyper- 

 leptus. The maxillary is long and low, with short preorbital portion, 

 which ends abruptly in the broad, rounded, pillar-like sheath of the 

 caniniform tooth ; the preorbital fossa is very deep and has a well defined 

 dorsal border ; the depth of these fossae, the great width of the muzzle in 

 front of them, and the shortness of the premaxillaries give a highly char- 

 acteristic appearance to this region of the skull ; dorsally, the facial por- 

 tion of the maxillary is curved toward the median line, overlapping the 



