THE DYNASTY OF FISHES. 239 



and is two formations lower than the oldest fish-remains of 

 Europe. 



We have now stirred up all the old bones the oldest 

 bones buried on our planet so far as we know. But I do 

 not think we have found the first fishes yet. There must have 

 been some forms still less like fishes than these. Perhaps if 

 we could carry the line back, we should find fish-like creatures 

 approximating more and more to crustacean creatures. There 

 was Pter-y-go '-tus in the Old World and America, and Eu-ryp r - 

 te-rus plentiful in America, with its extended pair of arms re- 

 minding one forcibly of the Pter-ich' '-thys or "Winged-fish" 

 of the Old Red Sandstone. There was Cephalaspis, with its 

 broad head-shield exceedingly similar to the shield of the 

 modern King-crab and some of the old trilobites. Other in- 

 timations exist of a possible near relationship between these 

 half completed vertebrates and the dying-out forms of Crusta- 

 ceans. But these are questions which must be left to the 

 future. 



These relations enable us to contemplate with new interest, 

 some of the despised fishes which live in our times. Our 

 sturgeons, gar-pikes, and sharks are the sparse representatives 

 of those ancient families which once sustained alone, the dig- 

 nity of the vertebrate type. In their forms was first 

 enshrined the conception of the vertebrate plan of structure 

 which was destined to remain on the earth under its various 

 modifications, until man, the thinking and ruling vertebrate, 

 should arrive. Of these ancient families, the placoderm was 

 destined to disappear with the Devonian, and without a suc- 

 cessor. The sturgeon-type has survived in a slender line of 

 representatives, to the human epoch. The cestraciont sharks 

 were probably differentiated into the various better known 

 families of modern sharks, but continue to our times, to exem- 

 plify the probable nature of old Onchus, patriarch of sharks. 

 The bony scaled ganoids more fish-like than any of the 

 others, both in form and scaly covering, were well represented 

 by Onych'odus. The power and numbers of their family con- 

 tinued to increase through Carboniferous and Mesozoic times; 



