INTRODUCTION 7 



large size, the body and tail are very long and slender, the pelvis 

 of the pelycosaurian or V aranosaurus type, and the feet appear 

 to be very much like those of the last-named genus, save that the 

 limbs are very much more slender. The genus seems to be very 

 closely allied to, possibly identical with, Kadaliosaurus from the 

 European Permian. 



I have given numerous figures of some of the most characteristic 

 smaller bones in this bone-bed, not only because of their unusual 

 perfection but because of their faunistic association. 



Permian of New Mexico 



Since the brief paper by Marsh in the American Journal of 

 Science for May, 1878, is rather inaccessible and isolated I have 

 quoted his descriptions in the discussions of his types, and here 

 give the introductory part of the paper as follows: 



The United States Survey of the Fortieth Parallel, in charge of Mr. Clarence 

 King, has made known the fact that a well-marked Permian horizon can 

 be distinguished in the Rocky Mountain region; and deposits considered of 

 this age are represented on the geological maps of that survey. This adds much 

 interest to the vertebrate fauna known from near this horizon, and probably 

 belonging to it, as hitherto no Permian vertebrates have been identified in this 

 country, although not uncommon in Europe. 



The Museum of Yale College contains an extensive series of reptilian 

 remains belonging to a peculiar lacustrine fauna, which includes also amphibi- 

 ans and fishes. These fossils are from several localities in the West, but 

 mainly from New Mexico, and the geological horizon appears to be in the upper 

 portion of the Permian. These reptilian remains are in excellent preservation, 

 and among them are several genera having the more important characters of the 

 Rhynchocephalia, of which the genus Hatter ia, of New Zealand, is the living 

 type. The principal points of agreement are the separate premaxillaries, the 

 immovable quadrate, and the biconcave vertebrae. Another character of 

 much interest is the presence of certain hypaxial elements of the vertebrae, 

 first observed by von Meyer in the Triassic genus Sphenosaurus, and called 

 by him intercentral bones (Zwichenwirbelbein [sic]). These wedge-shaped 

 bones are apparently the homologues of the cervical hypopophyses in the 

 Mosasauria, and of the subcaudal attachments in the Odontornithes, and a 

 few recent birds. These intercentral ossifications apparently exist in all the 

 reptilia yet found in this new fauna, and hence serve to distinguish it. With 

 this character is another of hardly less interest. The anterior rib-bearing 

 vertebrae preserved have three separate articular facets for the ribs; one on 

 the anterior part of the centrum for the head, and a double one above for the 



