EDENTATA OF THE SANTA CRUZ BEDS. 27 



Fifteen caudal vertebrae (Plate IV, fig. 2) in apparently uninterrupted 

 succession, are associated with one of the specimens ; the series, however, 

 is not complete, for another vertebra which is preserved, is evidently sepa- 

 rated from the fifteenth by a gap, and several of the terminal joints are 

 missing. These vertebras indicate a longer tail than has been observed in 

 any other Santa Cruz armadillo and one which probably was not as long 

 in proportion as that of Tatu, but was broader and more depressed. The 

 first caudal has a short, broad, somewhat depressed centrum, with trans- 

 versely oval and slightly concave faces ; on the ventral side are grooves, 

 which start from the hinder border of the transverse processes, converge 

 forward, enclosing between them a raised, triangular area. The neural 

 canal is low, but quite wide, and the neural spine very low, while the 

 zygapophyses are complete, though simple. The transverse processes are 

 remarkably long and straight, extending directly outward from the centrum 

 and slightly widened and thickened at the distal end. These processes, 

 which are much the most striking feature of the vertebra, are very similar 

 to those of the last sacral, and their breadth is nearly equal to the length 

 of the centrum. Passing backward toward the end of the tail, the centra 

 gradually become reduced in diameter, but increase in length ; none, 

 however, is more than moderately elongate and they are relatively much 

 shorter than the corresponding bones of Tatu. The maximum length is 

 reached in the sixth caudal and is maintained with hardly any change to 

 the fifteenth, and even the much more slender isolated vertebra, which may 

 be taken as the seventeenth, is almost as long as the fifteenth. All the 

 centra have the ventral grooves above described, but they gradually be- 

 come very obscure ; on vertebras one to four these grooves are continued 

 around the sides of the centra to the hinder opening of the neural canal. 

 Small haemapophyses for the attachment of chevron-bones are present on 

 all the caudals, except the first, and perhaps on that one also, but, if 

 so, they are very feebly developed. Zygapophyses cease quite abruptly 

 on the eighth vertebra, which has long anterior, but no posterior pro- 

 cesses. Metapophyses, on the other hand, persist on all of the caudals, 

 diminishing posteriorly. The neural canal diminishes rapidly, but re- 

 mains, as a fine, hair-like tube, as far back as the fifteenth vertebra, on 

 which it is, for most of its length, a very narrow groove ; no trace of 

 the canal appears on the ? seventeenth. The neural arch is high, especially 

 behind, where it carries the postzygapophyses, and even after the latter 



