86 



GEOLOGY. 



(Fig. 362). The forebears of the living gar -pikes and sturgeons took 

 precedence in numbers; the forerunners of the modern Amia (Fig. 



363,) were an important factor, and the 

 initial forms of the bony fishes (teleosts), 

 the dominant existing type, made their 

 appearance. The peculiar persistent family, 

 Coelacanthidce (Fig. 364), attained its maxi- 

 mum development. The earliest repre- 

 sentatives of the remarkable pycnodonts 

 came in with the early stages of the period. 

 The new aspect was markedly more 

 modern than that presented at the close 

 of the Paleozoic. 



(9) It was noted under the Trias that 

 certain land -reptiles went down to sea, 

 and introduced a new phase of vertebrate 

 mastery over the deep. From what has 

 just been said of the fishes, it appears 

 that, while doubtless suffering much from 

 the new dynasty, they maintained a 

 notable abundance and variety, and it 

 will be seen later that they outlived the 

 invading race, and resumed their former 

 place of dominance, in large degree, though 



Fig. 361. — A Jurassic skate, , ,, 



Squatina speciosa, about two- never Wholly. 



thirds natural size, from the Marine reptiles.— Of the four groups 



lithographic stone at Solen- . or 



hofen, Bavaria. (A. Smith of reptiles which went clown to the sea, 



the thalattosaurians, ichthyosaurians, ple- 

 siosaurians, and thalattosuchians, the first had apparently become wholly 

 extinct, while the last made its first appearance near the close of the 

 period. Of the other two, the ichthyosaurs, as the name implies, were the 

 most fish-like in appearance. They reached their highest development 

 in this period, and from the abundance and wide distribution of 

 their remains, it appears that they were very prolific, and probably 

 traversed every sea. Their adaptation to aquatic life is shown in 

 the complete transformation of the limbs into paddles (Figs. 365 and 

 366), in the reduction of the outline of the body to ichthyic lines 

 and proportions, in the sharp bending down of the vertebras of the 



