EDENTATA OF THE SANTA CRUZ BEDS. I 87 



MEASUREMENTS. 



Skull, length in median basal line 173 Length, occipital condyle to glenoid 



Skull, length in median line to anterior cavity 028 



border of maxillary 137 Length from occipital condyle to last tooth .077 



Skull, extreme length 189 Palate, length in median line (exclusive 



Cranium, length to anterior rim of orbit .118 of premaxilla) 060 



Face, length from orbit to anterior " width at 1 025 ' 



nares 048 " " " preorbital fossae 028 



Face, length from orbit to end of pre- " " "4 017 



maxillary 083 " " " 013 



Occiput, height 047 Mandible, length 140 



" width at base 062 " " of predentary beak. . . .049 



Cranium, width at postorbital constric- " " from condyle to ^ 065 



tion 033 " depth at ^ 028 



Cranium, width over lachrymals 065 " thickness at ^ 018 



Zygomatic arch, length 090 " height of coronoid 064 



Jugal, length of descending process 036 " " " condyle 045 



Vertebral Column and Ribs (Plate XXX). The vertebral column, 

 though well preserved, is not sufficiently complete to show the exact 

 number of vertebrae in each of the different regions, but it is highly 

 probable that the formula was as follows : C. 7 ; Th. 22 ; L. 3 ; S. 6 ; 

 Cd. 20 . The neck about equals the skull in length and is quite 

 slender, though relatively heavier than in some of the smaller species. 

 The atlas differs from that of all the Pleistocene genera in which this 

 vertebra is known, and is most like that of Mylodon, but is relatively 

 longer antero-posteriorly, narrower transversely and shallower dorso- 

 ventrally; the anterior cotyles, which are deeply concave, are not so 

 widely separated as in the last-named genus, and between them the in- 

 ferior arch is deeply notched, more so even than in Megatherium; the 

 posterior cotyles are quite large and sessile. The neural arch is thin and 

 but moderately curved and the spine is represented by a very small 

 tubercle ; the foramina for the first pair of spinal nerves are large and per- 

 forate the arch near the anterior border. The inferior arch is narrower 

 and shorter, but thicker and more curved than the neural and has a 

 hypapophysial tubercle ; the large facet for the odontoid process of the 

 axis is continuous with the posterior cotyles. The neural canal is lower 

 and wider than in Mylodon, but ventrally becomes much narrower, and 

 the tubercles for the attachment of the transverse ligament are not con- 

 spicuous. The transverse processes most resemble those of Mylodon, 



