534 S. W. WILLISTON 



son described all the presacral vertebrae of Eryops as having double- 

 headed ribs, attached to diapophysis and hypocentrum, while in 

 Cacops it is only the anterior vertebrae which articulate with the 

 hypocentrum and this is also clearly the condition in Dissorophus. 



So far these are all the described genera of rhachitomous amphibia 

 from the American Permian. The genus Cricotillus Case I suspect is 

 identical with Crossotelos Case, a " Microsaurian " amphibian, while 

 Cricotus is an embolomerous form. 



Recently Case has discovered that Otocoelus is identical with 

 Dissorophus, as indeed the figures given by Cope indicated. Whether 

 or not the genus Conodectes Cope is also a related temnospondyl it is 

 impossible to determine without examination of the type. The 

 description given by the author of the genus is utterly inadequate for 

 its recognition. 



Following is a taxonomic summary of the known American Per- 

 mian Amphibia. 



Caudata. 



Lysorophidae Williston, 1909 (Paterosauridae Broili, 1904). 

 Lysorophus Cope, 1877. 



tricarinatus Cope, 1877, Illinois, Texas, Oklahoma. 

 "Microsauria" (Diplocaulia Moodie). 

 Diplocaulidae Cope, 188 1. 

 Diplocaulus Cope, 1877. 



salamandroides Cope, 1877, Illinois, 

 magnicomis Cope, 1882, Texas, 

 limbatus Cope, 1896, Texas. 

 Copei Broili, 1904, Texas, 

 pusillus Broili, 1904, Texas. 

 Crossotelidae Williston, 1909. 



Crossotelos Case, 1903, Oklahoma. 

 , annulatus Case, 1903. 

 ? Cricotillus Case, 1903, Oklahoma, 

 brachydens Case, 1903. 

 Temnospondyli. 



Embolomeri. " 



Cricotidae Cope, 1884. 

 Cricotus Cope, 1873. 



heteroclitus Cope, 1875, Illinois, Kansas, 

 gibsoni Cope, 1877, Illinois, 

 crassidiscus Cope, 1884, Texas, 

 hypantricus Cope, 1884, Texas. 



