EDENTATA OF THE SANTA CRUZ BEDS. 9 



caudal vertebras, that have been collected, it is possible that such may 

 have been the case. 



Considerable variety is displayed in the dentition, though in no species 

 has any trace of enamel or of the milk-teeth been observed. The marked 

 diphyodontism of the modern Tain makes this fact somewhat surprising. 

 Premaxillary teeth and the corresponding mandibular teeth occur in two 

 genera, Proeutatus and Peltephilus, and in the latter they are so closely 

 approximated that the teeth of both upper and lower jaws form a continu- 

 ous series. Prosaedius and Stenotatus have teeth like those of most recent 



FIG. 2. 



Skulls of Santa Cruz armadillos, x f . a, Stegothcriitm tesselatiim ; b, Prozaedius exilis ; c, 

 Proeutatus lagena. 



armadillos, while in Proeutatus the teeth show an incipient division into 

 lobes and have a complex masticating surface, produced by layers of dentine 

 of different hardness and color, and with some resemblance to the teeth of 

 the glyptodonts. In Peltepliihts the teeth are sharply pointed and form what 

 appears to have been a formidable lacerating apparatus, while, finally, in 

 Stegotherium the dentition is in such an extreme state of reduction that 

 the animal must have been functionally all but edentulous. 



In all the known genera, except Peltephilus, the skull has a very 

 elongate and usually a slender rostrum, and, with the same exception, the 

 zygomatic arch has a prominent descending, suborbital process, which is 



