148 Evolution and Distribution of Fishes 



genera Ctenoptychius, Diplodus, Rhizodus and Palaeon- 

 iscus. It also contains Cythere^ Naiadites {Anthracomya) 

 and Spir-orbis. In the other beds which contain fish remains, 

 most of these consist of small lepidoganoids, but there are 

 occasional teeth and scales of large species of Rhizodus," 

 and also teeth of elasmobranch fishes of considerable size, 

 some of which he describes and figures. Later he adds: 

 "the larger ganoids, and the shark-like Diplodonts no 

 doubt preyed upon the smaller fishes, as the abundant 

 scales seen in their coprolites prove. The flat-toothed 

 sharks like Psammodus and Conchodiis may have ground 

 up the shells of Naiadites." 



Both authors, in describing the freshwater Albert 

 shales, were equally arrested by the conditions that sur- 

 rounded and in part caused wholesale destruction of, the 

 fishes. Thus in describing the five species of Rhadinichthys 

 [Palaeoniscus of Dawson) Dawson says (9(5:340) : "The 

 whole of these fishes have been preserved entire, the body 

 being perfectly flattened, and thrown into attitudes which 

 Imply that they were embedded when living, or immediately 

 after death. The material in which they are contained is 

 shown by its microscopical and chemical characters to have 

 been a vegetable muck or mud, and the fish were entirely 

 overwhelmed by it, in the manner of a bursting bog, or 

 were stiffled by the non-oxygenated water mixed with this 

 mud, and suddenly killed and embedded in the accumulating 

 sediment." Here, as in the frequent preservation of fish 

 and other organisms in the fossil state, sudden flood-plain 

 freshets might explain the results, though the sudden throw- 

 ing into the water of deleterious products seems more 

 likely 



Lambe draws an exact parallel between the Albert 

 beds and those of the Scottish Calciferous system. But 

 regarding the fishes he says: "they belong to the same 

 genera, but differ as to species." This, however clearly 

 indicates that some important and continuous land-connec- 

 tion united both areas, as the chart of Freeh sets forth. 



A noteworthy feature of these Albert shales is their 

 apparent Identity In color, consistence, and oil-content with 

 the oil-shales of the Scottish Calciferous system. Thus they 



