The Chondrostei and Holostei 319 



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 either over- 

 whelmed by it in the manner of a bursting bog, or were 

 stiffled by the non-oxygenated water mixed with mud, and 

 suddenly killed and embedded in the accumulating sediment. 

 That they occur in this perfect state, and in a limited thick- 

 ness of the deposit, may imply that at certain times they 

 were overwhelmed by the eruption of the foetid organic 

 mud into the water in which they lived. The bed is low 

 down in the Lower Carboniferous series, being the equiva- 

 lent of the Horton series of Nova Scotia; so that these 

 fishes are among the oldest that we know in the Carbonifer- 

 ous period." 



Lambe in continuing and extending Dawson's work 

 notes also the enormous abundance of the fish remains, 

 and says for Rliadin'ichthys alberti alone, that: "It evi- 

 dently swarmed in countless numbers in the waters of its 

 time." With it he also describes Canohius modulus and 

 three indigenous species of Elonichthys, of which E. browni 

 was probably commonest (Fig 18, p. 150). So in compar- 

 ing the Albert shales of New Brunswick with the Calcifer- 

 ous of Scotland he observes that the fishes "belong to the 

 same genera but differ as to species." Associated again 

 with these are the freshwater entomostracans Leaia leidyi, 

 Estheria, Beyrichia, and a rich land flora. Dawson and he 

 both note the highly bituminous nature of the Albert rocks. 

 Thus Lambe says that "at Albert mines and vicinity, certain 

 layers of the shale are replete with the remains of fishes of 

 the family Palaeoniscidae" and in "attaining a thickness 

 sometimes of five or six feet yield abundant oil and sulphate 

 of ammonia." He observes also that "the numberless re- 

 mains of fishes in some of the beds can be attributed only to 

 the occasional wholesale destruction of the fishes." 



By the time that the anadromous and the ultimately 

 marine elasmobranchs had fully invaded the sea (p. 280), 

 and were in some cases becoming fossilized in their teeth 



