1 70 Evolution and Distribution of Fishes 



Reviewing shortly the groups of Permian fishes, it 

 may be said that the elasmobranchs are represented by 

 six species of Pleuracanthus, three of Acanthodes, two of 

 Diplodus,, and one of Janassa and Wodnika. 



In distribution they extend more or less from Bohemia 

 to England, Illinois, and southward to Texas. Acanthodes 

 is the most persistent, for species are traced from the Lower 

 Old Red up to the Lower Permian; while Pleuracanthus, 

 Janassa and Diplodus extend up from the Lower Carbon- 

 iferous. The Dipnoans are known by the genera Concho- 

 poma and Sagenodus, the latter, which occurred in the Coal 

 Measures, being scarce in Europe, but showing a rich de- 

 velopment of species, from Illinois to Texas. According 

 also to Fritsch our present-day Neoceratodus of Australia 

 was anticipated already by a species of Ceratodus. 



Fig. 20. Amblypterus latus, from Lower Permian beds of Le- 

 bach, Saarbriicken, Rhenish Prussia. About one-half natural size. 

 (After Traquair.) 



The Crossopterygians were represented by two species 

 of Megalichthys and one of Coelacanthus, both genera 

 continued from the Carboniferous. The Chondrosteans 

 were probably the most abundant in individuals, and con- 

 sisted of Amblypterus (Fig. 20) and Palaeoniscus (Fig. 

 21), each with five or six species that extended more or 

 less across Europe, while Acrolepis, Elonichthys, Platy- 

 somus (Fig. 45, p. 281), Pygopterus and Thrissolepis are 

 less abundant. 



With the close of the Permian, and therefore of the 

 great Palaeozoic era, it can correctly be said that primitive 

 fishes first appeared in freshwaters and very largely per- 



