EDENTATA OF THE SANTA CRUZ BEDS. 17 



convex form seen in Tatu. The presphenoid is quite long and broad, 

 very thin and of nearly uniform width, so far as it is exposed in the roof 

 of the posterior nares. The alisphenoid is small and is perforated by the 

 foramen ovale, while its anterior edge forms the hinder border of the fora- 

 men rotundum ; the descending process is very short. The orbitosphenoid 

 seems to be somewhat larger, but the limits of the bone are hardly deter- 

 minable, as both skulls are injured in this region. 



The parietals are short and broad, descending farther upon the sides of 

 the cranium than in Tatu ; they form no sagittal crest, but only a narrow 

 sagittal area, which widens anteriorly to the frontal suture, and is clearly 

 demarcated from the temporal fossae by being raised well above them. 

 In Tatu this area is broader, but is very obscurely marked, while in the 

 fossil it is conspicuous, as it is not only raised, but its smoothness is in 

 decided contrast to the roughened surface of the remainder of the parietals. 

 Except near the anterior border, the sagittal area is much thickened and 

 filled with cancellous bone. 



The squamosal is a large bone, lower, but longer than the parietal, so 

 that it has a considerable connection with the frontal ; the suture with the 

 exoccipital is very short, the squamosal touching that bone by hardly 

 more than a corner, though it has a long suture with the mastoid portion 

 of the periotic, and it takes no share in the formation of the lambdoidal 

 crest. The auditory meatus makes a broad, deep notch in the squamosal. 

 A deep groove extends upon the side of the latter, its ventral and pos- 

 terior border being formed by a prolongation of the dorsal border of the 

 zygomatic process, though this border is much less elevated than in Tatu. 

 The glenoid cavity is altogether different from that of the modern genus, 

 being a narrow, elongate, longitudinal groove, with no trace of a post^- 

 glenoid process, and resembling that of a rodent rather than that of an 

 armadillo. In Tatu, on the other hand, this surface is elevated, square, 

 and nearly plane, and the postglenoid process, though much reduced, is 

 yet distinctly present. The zygomatic process is extremely short, almost 

 as short as in Tatu ; it is a shelf-like projection with raised external border 

 which, however, is not nearly so elevated as in the recent genus ; the 

 jugal covers it so that only a small tongue of the bone is externally 

 visible. 



The jugal is quite long, forming nearly the whole of the zygomatic arch 

 and is very different in shape from that of any existing armadillo ; its 



