EDENTATA OF THE SANTA CRUZ BEDS. 93 



the orbit, then after a long interval comes an opening which doubtless 

 represents the combined foramina rotundum and ovale, which is unusually 

 far back, internal to the glenoid cavity and very near the foramen lacerum 

 medium ; the foramen lacerum posterius is quite large, the condylar and 

 stylo-mastoid foramina small ; no glenoid foramen is apparent. 



Vertebra, Ribs and Sternum. The vertebral column is still incom- 

 pletely known, though in the La Plata Museum is the nearly entire neck 

 of one species, perhaps P. pimiilus, and in the Princeton collection is an 

 individual (No. 15,390) probably referable to P, strepens, which has frag- 

 mentary vertebrae from all regions of the column, and none of these dis- 

 plays any significant differences from those of any other contemporary 

 armadillo. As a whole, the neck is relatively more elongate than in other 

 Santa Cruz genera. The atlas is hardly so short as in the latter, and the 

 transverse processes do not rise so high above the neural arch as in Pro- 

 etitatus. In the young animal all of the cervical vertebrae are free, but in 

 the adult the axis is fused with the third and fourth vertebras ; the axis 

 proper has a short and very wide centrum, with large, widely separated 

 and nearly plane surfaces for the atlas, a massive neural arch and small, 

 subcircular neural canal, but no transverse processes ; the odontoid pro- 

 cess is heavy and bluntly conical. The compound vertebra of the adult 

 has long and depressed transverse processes, a remarkably high, hatchet- 

 shaped neural spine, which posteriorly extends over the neural arch of 

 the fifth cervical. The fifth and sixth vertebrae have very short, wide 

 centra, but the neural arches are broad and in striking contrast to the 

 slender, thread-like arches of Proeutatus. 



In the anterior thoracic region, the vertebrae have short, broad, de- 

 pressed and slightly opisthoccelous centra, very prominent transverse pro- 

 cesses and very long, tapering and slender neural spines. So far as can 

 be judged from their broken condition, the posterior thoracic and lumbar 

 vertebrae have accessory articular processes quite as complex as those of 

 the modern armadillos, two additional pairs of pre- and post-zygapoph- 

 yses occurring on one vertebra from near the hinder part of the thorax. 



The tail is stout and evidently quite long, for eighteen caudal vertebrae 

 are associated with one individual and the series is far from complete. 

 The vertebrae resemble those of Dasypus, but are relatively shorter ; in 

 the anterior caudal region the vertebrae have long, slender and depressed 

 transverse processes ; posteriorly these processes become shorter and 



