EDENTATA OF THE SANTA CRUZ BEDS. 15 



upper profile of the skull descends forward very gradually and almost un- 

 interruptedly from the occipital crest to the tip of the rostrum, but is made 

 slightly sinuous by the projection of the frontal sinuses, the posterior con- 

 vexity of the nasals and the upturning of the end of the rostrum. In one 

 of the specimens (No. 15,566) the frontal sinuses are very inconspicuous 

 externally, making this portion of the profile somewhat concave. In Tatu 

 the upper contour of the skull is quite similar, though modified by the 

 great development of the frontal sinuses and the maxillary antra. 



The occiput is high and inclined forward slightly, broad at the base, con- 

 tracting regularly and gradually to the top, resembling the occiput of Tatu 

 in shape, but is less square in outline, being broader ventrally and nar- 

 rower dorsally. As a whole, the occipital surface is convex transversely 

 and, in addition, the upper half displays three vertical ridges, of which the 

 median one, for the vermis of the cerebellum, is the most prominent, 

 though decidedly less so than in the recent genus. The lambdoidal crest 

 is almost obsolete, except near the dorsal summit, where it is quite thick 

 and prominent and is emarginated by a broad, rectangular notch, at the 

 bottom of which are two small but very deep, hemispherical fossae. In 

 Tatu a similar, but much less distinct notch is present, while the fossae are 

 almost obsolete. The foramen magnum is low and wide and, though 

 relatively higher than in the modern genus, is more like that in the latter 

 than that of Dasypus, being to a large extent formed by a broad, deep, 

 V-shaped notch of the basioccipital between the condyles. 



The bones of the occiput are so completely fused together that their 

 limits cannot be determined with certainty, but they seem to have quite 

 similar proportions to those of Tatu. The basioccipital is short and 

 broad, much wider posteriorly than anteriorly, as it" expands behind the 

 tympanic and periotic, much as in the last named genus ; it is convex 

 transversely has a low, curved transverse ridge, which is separated by a 

 shallow groove from the margin of the foramen magnum. In one of the 

 specimens there is a faintly marked median keel. On each side of what 

 is probably the line of suture with the basisphenoid, is a prominent, pitted 

 tubercle, doubtless for the recti antici tendons. The posterior part of the 

 basioccipital is bent downward at an obtuse angle, somewhat as in Tatu, 

 but more abruptly, and is thicker and more rounded. The exoccipitals are 

 broader than in the modern genus and are so extended that very little of 

 the squamosal is visible from behind, while in Tatu much of this bone is 



