58 Evolution and Distribution of Fishes 



of oil-strata, would also explain the subsequent formation 

 of secondary products of petroleum decomposition. 



Recently Engler has stated from experimental evidence, 

 that decomposition of animal oil is effected by two stages. 

 First, owing to bacterial action — and this we claim would 

 proceed much more rapidly and perfectly in freshwater 

 than in the sea — nitrogenous matters are eliminated, "the 

 action being automatically stopped almost as soon as the 

 fats are attacked." The second stage, clearly demonstrated 

 by Warren and Storer as well as confirmed by Engler's more 

 recent results, consists in the combined and continued action 

 of heat and pressure on the oils, though, according to 

 Engler, even this may be initiated by oil-splitting bacteria. 



The entire subject opens up many avenues for future 

 observation and experiment, especially in view of the 

 writer's claim that a freshwater and not a marine habitat 

 was through long ages typical for fishes. 



From all that has been adduced above then the writer 

 would conclude: (a) that many isolated fishes, or groups 

 of them in the fossilized state, show rich petroleum prod- 

 ucts around or within the specimens; (b) that petroleum 

 oils are usually found only where abundant fish remains 

 occur; (c) that sudden destruction of fish-life by direct 

 volcanic agency, and over wide expanses of water has 

 been recorded, and evidently also took place widely and 

 violently from late Silurian to Miocene age; (d) that 

 contrary to past opinion, and as is demonstrated in suc- 

 ceeding chapters, this took place wholly or almost wholly 

 in freshwater areas, and only in later Jurassic and succeed- 

 ing times did such occur in saltwater; (e) that the amount 

 of destruction and the widespread nature of it, as evidenced 

 by "bone-beds" of fishes, by bituminous schists, etc., would 

 amply account for all of the petroleum oil or gas, hitherto 

 removed by man from any strata; (f) that frequent sudden 

 entombment and preservation of fossil fishes were effected 

 by volcanic dust showers which accompanied or succeeded 

 such destructive agents as poisonous gases, earth and water 

 concussions, superheating of waters and other means; 

 (g) that the oils and fats, possibly even degenerate muscu- 

 lar tissue, set free abundant products from which petroleum 



