298 



PALEOZOIC TIME — DEVONIAN AGE. 



4. Vertebrates. — In the Devonian rocks of Great Britain and Europe, a 

 large number of species of fishes have been found ; and when we consider how 

 little likely fishes are to become buried and fossilized, we begin to appreciate 

 their vast abundance in the Age of Fishes. 



Among Ganoids, fig. 516 represents the Placoderm Pterichthys MUleri (as 

 restored by Pander), reduced to ljalf the natural size. The Goccosteus resembles 

 it in its plates, but has a longer tail, 'fitted for sculling by means of a fin along the 

 upper and under sides. Fig. 517, the Rhombifer Ganoid Cephalaspis Lyellii ; 

 figs. 517 a, 517 b, scales of the same; fig. 518, the Imbricate Ganoid Holopty- 

 chius ; fig. 518 a, scale, id. ; fig. 519, another Rhombifer, Dipterus maerolepi- 

 dotus. 



Figs. 517-519. 



17 



Ganoids.- 



-Fig. 517, Cephalaspis Lyellii ; 517 a, 6, Scales, id. ; 518, Holoptychius ; 518 a, 

 Scale, id. ; 519, Dipterus macrolepidotus ; 519 a, Scale, id. 



Asterolepis Asmusi Agassiz, whose remains occur both in Russia and Scot- 

 land, must have been 20 to 30 feet long. 



Reptiles. — Fig. 520, Telerpeton Elginense Mantell, a species found on the south 

 side of the Moray Firth, in a whitish sandstone rock which is regarded by most 



