FOSSIL FISHES. 



27 



One genus, Cheirolepis (Wall-ease 8a), remarkable for its very 

 minute scales, is known, from the Old Red Sandstone. The family 

 attained its maximum in the Carboniferous formation, being re- 



Fic. 42. — Macropomo, Chalk, Lewes (restored outline after Huxley), a, Jugular plates; 

 b, the ossified, air-bladder ; c, the pelvic bones. 



presented by Elonichtliys, JSJiadiniekihys, Nematoptycliius and 

 Gonatodus. 



To these several new genera have been recently added from the 

 Lower Carboniferous of Eskdale, Dumfriesshire [see Table-case 39). 



Palceoniscidcv are also abundant in the Permian rocks both of 

 England and the Continent (Fig. 47). 



In the Magnesian Limestone of Durham we have Pygoptems, 

 Acrolepis, and Palceoniscus, these 

 also occur in the Kupferschiefer of 

 Germany, and in the unteres-Eoth- 

 liegendes occur Amblypterus (Fig. 43) 

 and Bliabdolepis. In Fig. 43 are 

 given views (a) of four of the scales, 

 showing the outer surface, and (b) of 

 two of the scales, showing the inner 

 surface. Each of the rhomboidal 

 ganoid scales of Amblypterus has a 

 ridge on the inner surface which is 

 produced at one end into a projecting 



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

 manner in which tiles are pegged together on the roof of a house. 

 The Triassic scales known as Gyrolepis, and the teeth named 

 Sauriclithys, probably both belong to a Palseoniscid fish (Traquair). 

 In the English Lias are found Oxyynathus, Cosmolepis, and Thrisso- 

 notus. The Palceoniscidce do not extend upwards beyond the Lias. 



The Platysomidce (Wall-case 8b, and Table-case 39) are most 

 nearly related to the Palceoniscidce. They are confined to the 

 Carboniferous and Permian formations. 



Fig. 43. — Ganoid scales of Arably- 

 pterus striate.', Carbonifs. 



