APPEARANCE CF VERTEBRATE ANIMALS. 123 



especially, are represented by a great variety of species, some 

 of them nearly allied to their Silurian predecessors (Fig. io6), 

 others of forms and structure not dissimilar to those of the few 

 surviving representatives of the order, or altogether peculiar to 

 the Devonian (Fig. 107). So numerous are these fishes, and 

 of so many genera and species — and this not merely in one 

 region, but in widely separated parts of the world — that the 

 Devonian has not inaptly been called the reign of Ganoids. 



Fig. 106. — Devonian Placoganoid Fishes {Pterichthys cormUus, Cephalaspis Lyelli). 



As an illustration at once of the very peculiar forms of some 

 of these fishes and of their wide distribution, I figure here a 

 species of Cephalaspis (Fig. 105) found in the Lower Devonian 

 of Gasp^, in the same beds with some of the antique Devonian 

 plants described in the last chapter. 



A new and interesting light has recently been cast upon some 

 of the most anomalous of the ancient fishes by the study of 

 the now rare and peculiar species of the group of Dipnoi. 

 Two of these, belonging to the genus Lepidosiren^ are the 



