10 THE HISTORY OF THE PELYCOSAUEIA, WITH 



rugose, as in the Crocodiles. The crowns of the teeth are striate at the base, and the 

 latter is furrowed vertically. The teeth are not so thickly set as in the smaller species, 

 and the bases of the crowns are somewhat transverse. 



" Measurements. 



MM. 



Space occupied by ten anterior lower teeth 140 



Depth of lower jaw at symphysis 129" 



Antero-posterior extent of symphysis 25' 



Depth of clentary bone below seventh tooth 30* 



Width of dentary at this point 20- 



" The present species was about ten feet in length, and the largest reptile yet found 

 in this fauna. The remains are from New Mexico." 



The Ophiacodon mints is one of the Clej)sydropidse, and 0. grandis might be 

 Eryops Cope. 



The families " Nothodontidce " and " Sphenacodontidce " are, like the genera, 

 established without diagnosis. 



To this paper Cope 7 replied in The American Naturalist, June, 1878. He says that 

 the four species of reptiles are characterized by Marsh in a very insufficient manner. He 

 should not regard his article as suitable for notice in The Naturalist but for certain 

 assertions which it contains, and some circumstances connected with its publication. 

 The assertion that " hitherto no Permian vertebrates have been identified in this country, 

 although not uncommon in Europe," he declares the reverse of the fact, referring to his 

 paper in the Proceedings of the Academy of Natural Sciences of Philadelphia for 1875, 

 pp. 393-424, where some of the leading characters of the reptiles are pointed out; to his 

 papers in the Proceedings of the American Philosophical Society for May, 1877, pp. 52- 

 63, where several new species are described, and in the same journal for November, 1877, 

 in which other species are added, making the whole number up to twenty-one. He 

 then continues : " These papers Prof. Marsh has had the opportunity of seeing. Two 

 further notices of the vertebrates of the American Permian appeared on April 22, of 

 the present year (1878), in the May number of this journal, pp. 319 and 327. As the 

 corresponding number of the Am. Journ. Sci. and Arts was not issued before May 5 

 (perhaps a day or two sooner), Prof. Marsh had the opportunity of seeing these 

 also. They include references to seven new genera, for most of which the characters are 

 clearly pointed out. 



" The features common to the genera of the Permian, described by Marsh, are stated 

 by him to be those characteristic of the order RhynchocephaUa ; as I have already shown to 

 be the case with the forms described by me in the earliest as well as later papers of those 



