EDENTATA OF THE SANTA CRUZ BEDS. 73 



Vertebra, Ribs and Sternum. In all parts of the skeleton may be 

 observed a decided resemblance to Zaedyus, more than to any other 

 modern genus. The atlas is very like that of Zaedytts, so as to require 

 no particular description. As in the latter, the axis is fused with the third 

 cervical, and the compound vertebra differs little from that of the recent 

 genus ; the neural spine is less produced forward over the atlas and the 

 transverse processes are decidedly shorter and more slender and less thick- 

 ened at the distal end. In the other cervicals, the only differences from 

 those of Zaedyus are the absence of a neural spine from the fourth verte- 

 bra and the shorter and more slender transverse processes of all 



Of the thoracic series, the anterior three vertebrae, and the spines of the 

 fourth and fifth are known ; the centra diminish rapidly in breadth from 

 the first to the third, but increase in thickness, the anterior face of the first 

 being a mere plate with convex edge ; the neural spines are conspicuously 

 shorter, more slender and less steeply inclined than in Zaedyus and the 

 transverse processes are shorter and narrower, though of similar form and 

 similarly perforated by a vertical canal. 



At least three lumbars (Plate VI, fig. 10) were present, that number 

 being still attached to the pelvis in one individual ; they also resemble 

 the corresponding vertebrae of Zaedyus, but have somewhat smaller and 

 lighter centra, with more prominent paired ventral processes and decidedly 

 longer transverse processes. The zygapophyses and accessory articular 

 processes are quite as complex as in the modern genus, but the meta- 

 pqphyses are shorter and more slender. 



Of the sacrum, only the anterior half has been recovered and this bears 

 a close resemblance to the same part of Zaedyus, except that the median 

 ventral keel is more prominent and the fossa on each side of it corre- 

 spondingly deeper. 



Only one caudal vertebra, from near the hinder end of the series, has 

 yet been found, and this indicates a stout and elongate tail. Two 

 chevron-bones have also been obtained, one of them not unlike that 

 attached to the second and third caudals in the recent genus, though the 

 distal end is less expanded ; it is short, broad, heavy and perforated by a 

 canal ; the other resembles the sixth chevron of the modern genus and has 

 the canal converted into an open groove. 



The ribs are so much like those of Zaedytis that they require but a 

 very brief description ; the first rib has a rather more distinct and in- 



