137 



These were covered, with hard, en- Chimeras which flourished from close 

 amel-coated scales or bony plates, of Silurian also became extinct. Many 

 Some were short and heavy and en- ganoids became extinct, but other 

 tirely' encased in a covering of large ganoids came into existence to take 

 bony plates. They were evidently any- their places. The ganoids most nearly 

 thing but pretty and their movements like our modern sturgeons increased 

 in the water must have been extremely during the last of the Devonian and re- 

 awkward. Others were formed much tained their prominence to the close 

 after our own ideas of fishes. These of the Carboniferous. The slow-mov- 

 bore much resemblance to our gar- ing, heavily plated ganoids passed 

 pikes, the lung fish of the Nile and the away. They ruled during the De- 

 lung fish of Australia, and the worth- vonian age, but could not suit them- 

 less dog fish of our own fresh waters, selves to the new conditions at begin- 

 Anglers and fishermen all despise ning of the Carboniferous. While 

 these fishes now, yet in Devonian times fishes were numerous and large in the 

 the fishes most nearly like them were Devonian, throughout the Carbonif- 

 evidently the most handsome and erous they began to decline. By this 

 graceful of all fishes then living. It time the land area had much increased, 

 appears as if fishes in those days did land plants became very abundant, 

 not fight each other. They found there were immense forests of tropical 

 abundant sea room and plenty of food vegetation, great swamps and peat 

 in the form of invertebrates. Of course bogs all of which later sank below 

 it is quite probable that many fish-like sea level became covered up and 

 animals existed at this time, but pos- changed into coal. Immense lizards 

 sessing no hard parts and were not lived in these forests and along the sea 

 preserved as fossils; these could not be- shores; these were the first land ani- 

 come at all important for the sea was mals. At the close of the Carbonifer- 

 too full of large animals of all classes ous great changes took place ; greater 

 which were so well protected with a changes than at any time since the 

 coat of mail and so hostile that those close of the Archaean. So marked 

 less favorably situated could not exist were the changes at this time that it 

 in any great numbers. At the close of marks a new era in the geological his- 

 the Devonian many changes took tory of the earth. All preceding the 

 place. The rocks of this formation, close of the Carboniferous is regarded 

 which now form a portion of the as ancient geology ; all since then as 

 earth's surface, rose out of the water, modern geology. It was at this time 

 the land area thus considerably in- that plants and animals were repre- 

 creased, the seasons, such as they were sented by new forms more like those 

 then, became more marked ; many in- now living. The geological age fol- 

 land seas were formed. These changes lowing the Carboniferous is the Trias- 

 were more or less gradual, but not so sic. With this age began our modern 

 much so that the fishes living then sharks and fishes. They did not be- 

 could not suit themselves to the new come abundant until the Jurassic and 

 conditions. Those fishes which had Cretaceous. All of the earlier sharks 

 flourished for generations had become had strong spines in front of each dor- 

 accustomed to easy living and certain sal fin and broad teeth made for crush- 

 fixed ways, could not adapt themselves ing. One form of these known as 

 to changing conditions, and so became . Cestracionts were very abundant till the 

 extinct. The Pteraspids, the earliest end of the Cretaceous. In the early 

 forms to appear ; the Pterichthys, in Triassic they began to decline and the 

 fact, all forms which bear any resem- sharks, with pointed teeth, increased, 

 blance to our present lampreys, or These sharks, with pointed teeth, but 

 which may prove a close relative of rounded on the edges, commenced 

 the earlier ganoids, became extinct at back in the Carboniferous. During 

 close of the Devonian. The early the Triassic the sharks, with lancet- 



