1 66 Evolution and Distribution of Fishes 



fishes and amphibians, some of the last being of large size 

 and unwieldy build. 



If now we compare the statements made as to the 7ion- 

 marine Permian organisms, the lists of fossil fishes given, 

 the relation of these physically and biologically, the prac- 

 tical absence of fish records from the marine rocks, and 

 the affinities of these fishes with preceding and succeeding 

 fish-faunas, the observations of Geinitz and Fritsch for 

 Bohemia, and of Case for the Western States and specially 

 Texas, are fairly typical for other areas. Amongst the 

 fishes, representatives of the selachian or elasmobranch, 

 dipnoan, crossopterygian and chondrostean groups are all 

 known. And of these Case says: "There are no forms 

 which can be called distinctly marine." 



But Fritsch, in speaking of the life-conditions of the 

 elasmobranchs says: "At the time of the Permian for- 

 mation, the Xenacanthidae in Bohemia probably lived in 

 brakish water at the months of rivers, and utilized as food 

 the palaeoniscids, the acanthodians, and many other ani- 

 mals, which the rivers brought from the dr>'-lands to the 

 sea during floods." But as if largely or wholly to contra- 

 dict or minimize the "brakish water" statement he then 

 adds: "in company with the Xenacanthidae, we encounter 

 beside the Palaeoniscidae and Xenacanthidae likewise stego- 

 cephalids, myriapods, estheriae, and insects, which were 

 brought down from the dry land." Now in giving "stego- 

 cephalids" it should be observed that all amphibians are 

 intolerant of even brakish water, and further the entire 

 assemblage suggests only lacustrine or fluviatile sur- 

 roundings. 



By what catastrophe the elasmobranch fish-life of the 

 Carboniferous seas was virtually wiped out, we can as yet 

 only surmise. But that such actually happened will be 

 fully set forth in another section (p. 286). 



The Carbo-Permian beds of America cover a large area 

 included in North-West Texas, Oklahoma, New Mexico, 

 and Kansas. Cummins (725:186) and Gordon {126:21) 

 recognize three zones; (a) a lowest or Wichita, the deep- 

 est beds of which are in part marine, in part freshwater, 

 and decidedly suggest their being top-beds of the Carboni- 



