LEPIDOGANOIDEI. 



161 



continental and American coal formations, the scales are 

 smooth; e.g., in P.fultus, from North America, P. Dv.vernotji 

 and P. minutus, from the coal beds of Miinster Appel. In 

 the Palceonisci from the Permian copper schales and zech- 

 stein, the scales are striate or punctate. The Paloeoniscvs 



Fig. 70. 

 Falceoniscus (Permian). 



Freieslebeni is the most common, and was the first recognized 

 species of the genus ; of which there are forty known species, 

 chiefly from carboniferous and Permian eras : one from the 

 Keuper beds at Eowington, War- 

 wickshire, appears to be the last 

 representative of the genus : it is 

 the Palceoniscus sivperstes of Egerton. 

 Amhlypterus, with a geological 

 range like that of Palceoniscus, differs 

 in its shorter and deeper tail, and 

 larger body-fins, which are devoid of 

 anterior spines. In fig. 71, a indicates the outer surface of parts 

 of two series of the rhomboidal ganoid scales ; and b the inner 

 surface of two scales, shewing the ridge produced at one end 

 into a projecting peg, which fits into a notch of the next scale, in 

 the way that tiles are pegged together in the roof of a house. 

 The species affording the above structure is the Amhlypterus 

 •striatus from the coal formations at Newhaven, other species 

 of Amhlypterus have left their remains in the muschelkalk, 

 at which triassic period the genus seems to have passed 

 away. 



M 



Scales of Amhlypterus striatus 

 (Carboniferous). 



