Harper's New Monthly Magazine Volume 104 December 1901 to May 1902 . er race offishes, some of them leaving no suc-cessors. Nor could the approach of suchcatastrophes have slackened the warwaged by almost every race against itsfellows, and by the larger air-breathingforms against all, even if they had beencapable of appreciating it. Their liveswere one whole circuit of destruction,unchecked by the influences which atpresent prevail. Does the geological rec-ord show, for instance, that the giantfish-destroyers swept the primitive seasbarren by their voracity; was the bal-ance maintained; or did
Harper's New Monthly Magazine Volume 104 December 1901 to May 1902 . er race offishes, some of them leaving no suc-cessors. Nor could the approach of suchcatastrophes have slackened the warwaged by almost every race against itsfellows, and by the larger air-breathingforms against all, even if they had beencapable of appreciating it. Their liveswere one whole circuit of destruction,unchecked by the influences which atpresent prevail. Does the geological rec-ord show, for instance, that the giantfish-destroyers swept the primitive seasbarren by their voracity; was the bal-ance maintained; or did this conditiontend to the increase of the fishes? While the gigantic Dinichthys — ofthe Devonian rocks of North Americaand of the Old Red Sandstone—with itsmailed head three feet in length, andjaws armed with formidable teeth, andthe powerful Rhizodus, and perhaps theLabyrinthodonts of the Carboniferoussystem, are examples of great destroyersof fishes in their times, they held a sub-ordinate position to those which follow-ed in the Triassic seas. Teeming with. Fig. of large Shark dredged Challenger in the Pacific(Nearly natural size^ fishes, as our own now are, those ancientoceans differed in so far as their finnytribes were kept in check solely by theirfellows and the predaceous air-breathingreptiles or other types of the in that age of reptiles, theJurassic, gigantic reptilians took theplace of the fish-eating whales of laterages, and caused an enormous drain onfish life. These included large crocodili-ans—eighteen feet long—which venturedseaward to a much greater distance thanthe living gavial of the Ganges. More-over, their number and their gigantic sizecounterbalanced the agencies man nowputs in force against the fishes. The largest Ichthyosaurs were be-tween thirty and forty feet in length,and occurred in considerable numbersin a comparatively limited area duringthe long period stretching from theupper Triassic and Rhsetic to theChalk.
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