EDENTATA OF THE SANTA CRUZ BEDS. 71 



from the cranial roof proper by the forward curvature of the lambdoidal 

 crest. The mastoid portion of the periotic ends in a long, recurved mas- 

 toid process, which is closely applied to the tympanic and forms the pos- 

 terior wall of the external meatus. The tympanic is inflated into a small, 

 but distinct bulla, thus agreeing with Dasypus and Zaedyus and differing 

 from the other recent genera ; the bulla is not so large as in the two 

 modern genera named and is so far incomplete that it is deeply notched 

 from behind in a very peculiar and characteristic manner ; another difference 

 from the two recent genera is in the shape of the external meatus, which is 

 not a tube, but an irregular opening, the anterior lip of which is formed by the 

 tympanic and the posterior by the mastoid and posttympanic processes. 



The parietals are large, almost square bones, with finely pitted surface ; 

 posteriorly they form very short, wing-like extensions on each side of the 

 supraoccipital ; no sagittal crest is present, but a sagittal area may be 

 distinguished by its smoother texture. The squamosal is very low, but 

 elongate ; the glenoid cavity is placed well above the level of the teeth 

 and is small and slightly convex but with a deep fossa behind it ; the 

 postglenoid process is very small, but the prominent anterior lip of the 

 auditory meatus answers the same purpose ; the posttympanic process is 

 quite long, but is not conspicuous, because of its close adhesion to the 

 mastoid. The zygomatic process has about the same relative length as 

 in Zaedyus, but is rather more slender and compressed, and less extended 

 over the jugal, which is unlike that of any recent species ; its anterior por- 

 tion is thin and plate-like, forming, with the zygomatic process of the 

 maxillary, a distinct suborbital process; the posterior portion, however, 

 rapidly contracts to a slender, rod-like shape ; the dorsal margin is very 

 concave and somewhat flared outward. Although smaller than in 

 Zaedyus, the lachrymal is quite large, and extends downward to a con- 

 nection with the jugal ; the foramen is small, but is conspicuously placed 

 on the margin of the orbit. 



The frontals are large and receive an hour-glass shape from the post- 

 orbital constriction ; the sagittal area is continued from the parietals, but 

 its borders soon diverge to form the rather better defined supraorbital 

 ridges, but no postorbital process is indicated ; each frontal is raised into 

 a low eminence by the sinus, but the two are separated by a median de- 

 pression ; no nasal processes are formed. The nasals are very long, nar- 

 row and splint-like ; actually and relatively, they are longer than those 



