EDENTATA OF THE SANTA CRUZ BEDS. 183 



occipital crest to the parietal eminence, which is on a line with the glen- 

 oid cavity ; forward of this, the contour becomes concave at the postor- 

 bital constriction, whence it rises and becomes convex at the frontal sinus, 

 descending again very gradually to the muzzle. The cranium is long and 

 the face short, though much less shortened than in most other species of 

 the genus, a difference due chiefly to the relative development of the pre- 

 maxillae and the mandibular beak, which in the present species are very 

 much as in the Pleistocene genus Nothrotherium (Coelodon). 



As a whole, the occiput (Plate XXXIII, fig. i) has a shape resembling 

 that of Megalonyx, but is inclined gently backward instead of forward ; it 

 has a broad median vertical prominence, with a broad, shallow fossa on 

 each side of it ; the prominence projects quite strongly above the foramen 

 magnum, making the latter present downward rather than backward. The 

 crest is distinct but not prominent. All the elements of the occiput have 

 coalesced and the sutures are no longer visible, but the shape of these 

 bones may be inferred from a comparison with other species. The basi- 

 occipital is narrower and more convex than in Nothrotheriitm and on its 

 posterior half are two lateral fossae separated by an ill-defined median 

 ridge. The condyles are conspicuously larger than in the Pleistocene 

 genus, but not so widely separated ; they are also broader transversely 

 and taper more to the external ends. The exoccipitals are low and broad, 

 forming relatively little of the occipital surface, and the paroccipital pro- 

 cesses are almost obsolete. The supraoccipital is large and is reflected 

 quite extensively upon the roof of the cranium, between the divergent 

 parietals. 



The mastoid portion of the periotic is exposed o'n the surface of the 

 skull, but is not demarcated by fossae from the exoccipital and squamosal, 

 as it is in many other species of this genus ; a short but well defined 

 mastoid process is present, with distal facet for the hyoid. 



As usual, the parietals are very large ; they have no sagittal crest, except 

 near the anterior end, where the crest is very low, but quite distinct. The 

 temporal surface is everywhere convex, in marked contrast to most of the 

 Pleistocene genera, in which this surface is more or less concave. The 

 frontals are long and are made convex by the sinuses, with a moderate 

 depression along the median line ; the postorbital constriction is well 

 marked and in this region the frontals bear the sagittal crest, which is 

 longer than the parietal portion ; the crest does not bifurcate anteriorly 



