HISTORICAL REVIEW. 



The first mention of Permian vertebrates in North America occurs in 

 a description by Cope (20) of a small collection of fossils made by Dr. 

 J. C. Winslow, in the vicinity of Danville, Illinois. Cope identified four 

 forms, a Pelycosaur Clepsydrops colled, an amphibian Cricotus heteroclitus 

 (regarded by him at the time as a rhyncocephalian reptile related to Clepsy- 

 drops), and two fishes, a dipnoan Ceratodus vinslovii, and a shark Diplodus sp. 

 The beds from which these fossils were obtained were regarded as belonging 

 to the Triassic or Permian age, " since on the one hand Reptilia have not been 

 found in the coal measures, nor on the other hand has the genus Diplodus 

 been found above the Carboniferous series of rocks." 



A second lot of fossils sent to Cope by Dr. Winslow and a lot obtained by 

 Mr. William Gurley permitted him to extend his observations and descrip- 

 tions (2i). In this paper Cope mentioned or described as new: 



Strigilina lingucsformis gen. et sp. nov. Petalodontidarum. 

 Selachii: 



Diplodus {?) compressus Newberry. 

 Dipnoi: 



Ceratodus vinslovii. 



Ctratodus paucicristatus. 



Ctenodus {ossatus. 



Ctenodus gurleyanus. 

 Crossoptcrygia: 



Peplorhina arctata. 

 Amphibia: 



Cricotus heteroclitus. 



A renewed consideration of the fauna confirmed Cope in his previous idea 

 as to the age of the beds: "The present fauna must then be placed above the 

 Coal Measures, and the horizon will correspond more nearly with the Per- 

 mian than with any other embraced in the system." The position is reported 

 on the authority of Dr. Winslow to be near the top of the Coal Measures and 

 to be marked No. 15 in Prof. F. H. Bradley's section of the "Coal Measures 

 of Vermilion County, Illinois" (Geol. Survey, Illinois, vol. iv, p. 245). 



Later in the same year Cope (22) added to the list of animals from the 

 Permian of Illinois: 



Amphibia: Fishes: 



Cricotus gibsoni. Strigilina gurleiana. 



Cricotus discophorus. Ctenodus pusitlus. 



Lysorophus tricarinatus. Orthacanthus quadriseriatus. 

 Diplocaulus salamandroides. 

 Eryops megacephalus. 



