EDENTATA OF THE SANTA CRUZ BEDS. 91 



peculiarity of seeming to perforate the zygomatic arch, in a manner that 

 does not occur in any other known armadillo. The mastoid appears to be 

 quite extensively exposed on the occipital surface, ending in a large and 

 bulbous, but not prominent mastoid process, which is separated from the 

 posttympanic by a deep notch. 



The parietals are very large, forming nearly the entire roof of the cere- 

 bral fossa and extending to the postorbital constriction ; a sagittal crest is 

 present, but differs much in development in the various species. The 

 squamosal is long and low and its surface is roughened by pits and by 

 several conspicuous vascular foramina ; the glenoid cavity is unlike that of 

 any other contemporary armadillo in being a clearly defined, broad and 

 shallow fossa, which is placed very low down upon the side of the cranium ; 

 the posttympanic process is very small. As Ameghino has pointed out 

 ('94^7, 175), there appears to be a suture between the squamosal proper and 

 the zygomatic process, which he regards as the homologue of the quad- 

 rate ; but the relation is far from clear. The zygomatic process is short, 

 slender, laterally compressed and almost straight ; it does not, as in other 

 armadillos, curve downward, but is nearly horizontal, or even slightly 

 upturned. The jugal is quite elongate, slender, compressed and some- 

 what curved and extends forward to a contact with the lachrymal ; at the 

 posterior end is a feebly marked postorbital process. Alone among known 

 Santa Cruz edentates, Peltephihis has no suborbital process from the zygo- 

 matic arch. 



The lachrymal is quite a large bone, extending upon the face to a con- 

 tact with the nasal ; the foramen is small and placed within the rim of the 

 orbit. The frontals are shorter than the parietals and gradually expand 

 anteriorly over the orbits, with very short postorbital processes, below each 

 of which is a small vascular foramen ; the forehead descends quite steeply 

 forward and displays but a slight indication of sinuses in the form of two 

 very inconspicuous and widely separated swellings ; the nasal suture is 

 concave, but there are no nasal processes ; on the sides of the skull, the 

 frontals descend to reach the squamosals, ali- and orbito-sphenoids, and 

 in the hinder part of each orbit is a ridge on the frontal, which partly 

 encloses and conceals the optic foramen and the foramen lacerum anterius. 



The nasals are short and broad and are therefore in striking contrast to 

 the long, narrow and splint-like bones of other Santa Cruz genera ; doubt- 

 less in correlation with the horn-like scutes which they support, these 



