Summary of Conclusions Reached 513 



fishes Lepldosteans were then abundant from Wyoming 

 to Germany, The Green River shales of the States, the 

 Bituminous schists of East Brazil, and corresponding beds 

 of Europe had a fauna that showed much in common. 



But a striking fact is that the genera of Cretaceous 

 teleosts were practically obliterated, and a new set of 

 Eocene types — evolving largely apparently amid the great 

 N. American lakes, spread abroad to replace those destroy- 

 ed. A like obliteration of marine genera also occurred. 

 But as already noted quite a number of Cretaceous elasmo- 

 branch genera — about 15 in all — persisted to our time. 



The great "nummulitic sea" stretched at this period 

 across Europe and Central Asia on to Japan at least, and 

 received heavy nummulitic limestone deposits. Of recorded 

 Eocene teleost fishes 52 genera are wholly or largely fresh- 

 water, and 47 genera are purely marine. There is clear 

 evidence then of two successive teleostean migrations from 

 a freshwater to a marine life. First "from freshwater 

 ganoid ancestors, belonging to Pachycormidae, Aspidorhyn- 

 chidae, Pholidophoridae and Leptolepidae, originated the 

 late Jurassic or Cretaceous families Saurodontidae, Holo- 

 sauridae, Enchodontidae and others. After these were 

 largely blotted out at close of the Cretaceous, a new sea- 

 ward migration of Clupeidae, Aphredoderidae, Percidae, 

 etc. then took place. During Oligo-Miocene time varying 

 elevations and depressions of land occurred. S. America 

 and Africa, also Europe and N. America, which had hither- 

 to been connected by a southern and a northern bridge, be- 

 came sundered. Of deposits rich in organic remains, the 

 great east-west Oligo-Miocene group of strata, that stretch- 

 ed from France through Austria, Bulgaria, the Caucasus, 

 and S. Asia to Japan, was a marine group that included 

 several important fishbeds — the Amphisyle, the Meletta 

 (or menilite), and at least two others higher in position. 

 Great supplies of petroleum are now got from these. Suess 

 suspected that the vast accumulations of fossil fishes, and 

 the oil of the fish shales or of nearby porous rock, might 

 be explained by origin of the latter from the former. The 

 fishes and petroleum were here again marine. But numer- 

 ous areas in Central and S. France, in N. and S. Italy, in 



