136 AMERICAN PERMIAN VERTEBRATES 



contact could not be secured. In its porous texture and peculiar 

 black, glossy exterior it agrees perfectly with the lower extremity 

 of the spine, and is unlike other bones in the same lot. The height 

 of the spine as drawn is two hundred and eighty millimeters, 

 considerably more than twice that of the specimens described by 

 Case (one hundred and thirteen millimeters). The antero-pos- 

 terior expansion of the upper extremity is nearly fifty-five mil- 

 limeters, while the length of the centrum is but twenty-three 

 millimeters. 



This spine is most extraordinary. It is very thin and flat 

 throughout, save at the lower portion, where it changes into the 

 oval stem. The upper border, also, is a trifle thicker and it has 

 a gentle sigmoid curvature, which, however, I attribute to post- 

 mortem causes. On the lower part, especially, there are longi- 

 tudinal, somewhat inosculating ridges, and, scattered irregularly 

 over the bone, are a considerable number of small, irregular bosses, 

 or excrescences. Throughout this portion of the spine that is, 

 above the oval pedicel the anterior and posterior borders show 

 narrow groovings for ligamentous attachments. Associated with 

 these spines are a few fragments of another, apparently from the 

 same animal, and so far as they go, quite identical with the one 

 figured. 



The spine figured in Plate XXXVII, Fig. 6, natural size, I at 

 first ascribed to an amphibian, and possibly correctly, but, because 

 of the almost identical appearance of the bosses, it would seem 

 almost certain that it belongs in the same creature as do the longer 

 spines. It resembles very much a lumbar spine of Naosaurus in 

 its peculiar curvature. Above the zygapophyses, as in the long 

 spine, the bone is nearly cylindrical or slightly oval in cross-section. 

 But this thickness is retained throughout or is even greater at the 

 beginning and the end of the rugosities; and the upper extremity 

 is expanded somewhat, club-shaped. The nodular excrescences 

 are strongly protuberant, very irregular in position and scarcely 

 symmetrical on the two sides. No reptilian centra are preserved, 

 or at least have been so far discovered in the collection, to which 

 this spine could be attached; indeed, the arch is quite similar in 

 form to those of Eryops, found associated with the specimen. There 



