EDENTATA OF THE SANTA CRUZ BEDS. 335 



Hapalops and of a different shape, owing to its greater height ; the ridge 

 formed by the coalesced spines is high and has a much thickened free border. 

 Only on the last two vertebrae are the transverse processes preserved ; here, 

 they are long and very heavy and are completely fused with the ischia, 

 beyond which the distal ends project as short and massive protuberances. 



Although of a similar type to those of the contemporary Megalonyc hides, 

 the caudal vertebrae have a decided resemblance to those of Megatherium, 

 especially in their massiveness. The first caudal (Plate LX, fig. 6) has 

 a short, very heavy, block-like centrum, with two pairs of chevron-facets, 

 of which the anterior pair is the smaller, though far better developed 

 than in any of the preceding genera ; in the latter a vascular groove on 

 each side leads around the side of the centrum and behind the transverse 

 process into the neural canal ; in the present species the ventral portion 

 of this groove is converted into a canal, forming a conspicuous foramen 

 at the base of the transverse process, and another external to the pos- 

 terior chevron-facet. The neural canal is very large, far higher than in 

 Hapalops, and the pedicles of the arch are much more massive, as is also 

 the short spine ; the zygapophyses are remarkably heavy and there are no 

 distinct metapophyses. The transverse processes are relatively somewhat 

 shorter than in Hapalops and extend more obliquely backward, but are 

 very much heavier and more expanded at the distal end. 



Other caudal vertebras preserved are the second, the ? sixth and part of 

 the ? tenth ; in all the centrum remains of nearly the same length, but with 

 diminishing diameters, and the anterior pair of chevron-facets are much 

 smaller than the posterior pair and quite widely separated from them ; 

 the processes diminish in the usual gradual manner, but their remark- 

 able heaviness is characteristic of them throughout. In the ? sixth the 

 transverse processes are much shorter and thinner than in the first or 

 second, but are broader, especially at the distal end. Apparently, the 

 tail in the present species was decidedly heavier than in the Santa Cruz 

 Megalonychidce, but relatively somewhat longer and more slender than in 

 Megatherium. 



The ribs are broader than in any of the preceding genera, approximating 

 the proportions of Megatherium and Mylodon. The first rib is very short, 

 but with a decided lateral curvature, making the inner border strongly con- 

 cave ; the broad side is turned forward and the outer border is quite thick ; 

 the neck is long and slender, projecting inward almost at right angles 



