SYSTEMATIC REVISION 61 



on shanks which rise above the parapet of the jaw, but have a deeper attachment 

 on the inner side, being thus partially pleurodont. The crowns are swollen at the 

 base as in the maxillary teeth, but the apices are more produced, being regularly 

 conic. The apices are all lost. The teeth belong to a rather larger animal than 

 the one described above, and perhaps to another species. 



"Measurements. 



M 



"Length of a series of eleven maxillary teeth °-°37 



Diameters of the crown of a maxillary tooth: 



Longitudinal 004 



Transverse 003 



Distance from ninth tooth to anterior palatine co6" 



Revised description: The specimen shows a row of cheek teeth in a fragment 

 of a badly crushed skull, and several loose teeth in the matrix. It is impossible 

 to tell whether the teeth described by Cope are in position or not. The only charac- 

 ter by which these teeth can be distinguished from those of P. cordatus is that the 

 apices are drawn out sharply into a fine point. This point would very quickly be 

 worn away and leave the characteristic blunt cone of P. cordatus; it is very possible 

 that the presence or absence of the sharp points is but a character of age. The 

 species is very doubtful. 



INCERTAE SEDIS. 



Genus DESMOSPONDYLUS Williston. (Plate II, figs. 4, 5.) 



Desmospondylus anomalus Williston. 



Case, Joum. Geol. vol. vn, p. 718, pi. in, figs. 4a and 4b. 

 Williston, Bull. Am. Geol. Soc, vol. XXI, 1910, p. 280. 



Type: A humerus. No. 6541 University of Chicago. From Vermilion County, 

 Illinois. 



This specimen was recognized by Case in 1900 as reptilian in character and 

 probably cotylosaurian. Its publication was reserved for this volume. The dis- 

 covery of additional material by Williston permitted him to give a more complete 

 description, which is quoted below: 



"The vertebrae, of which there are 20 or more centra and fragmentary arches, 

 in addition to the connected series of 7 or 8, present some extraordinary char- 

 acters — characters which are very suggestive of amphibian affinities, annectant 

 between the rhachitomous and holospondylous types. The centra, coming all of 

 them apparently from the posterior dorsal region and the tail, are short, almost disk- 

 like, deeply concave, with a small perforating foramen. The arches are entirely 

 free; the sutural surface for their attachment is extensive, situated on the anterior 

 three-fourths of the centrum and extending downward on the front margin to below 

 the middle. Back of this sutural surface there is a similar beveled surface extending 

 about one-fourth of the length of the centrum, which also reaches down on the 

 posterior side to the middle of the centrum. The arches are very low, with a rudi- 

 mentary spine only, resembling the arches of Labidosaurus or Captorhinus. The 

 zygapophyses are very large and broad, with their surfaces nearly horizontal. 

 Below and back of the anterior zygapophyses there is, on either side, a distinct 

 diapophysis, on the more anterior vertebrae standing out prominently, on the poster- 

 ior ones a mere rugosity. Lying by the sides of these processes were a number of 

 small ribs, which seem to have been single-headed, inasmuch as no double-headed 

 ribs were found in the matrix. However, as Labidosaurus has quite this form of 



