1915-] SCHUCHERT— BLACK SHALE DEPOSITION. 261 



made up of land and marine forms plus fishes, most of which appear 

 to be of fresh water habitat. The only common fossils are the 

 ganoid Palceoniscus freiesleheni, Lingula credneri, " Asterias" 

 bituniinosa (problematic), and the small bivalves Nucitla beyrichi 

 and Bakeivellia antiqiia (sometimes in colonies). In other words, 

 the life consists of land-derived forms (3 vertebrates and 11 plants), 

 fishes (5 probably marine and certainly bottom-feeding, and 12 

 apparently of river origin), and 22 marine invertebrates all but one 

 of which are forms living on the bottom of the sea, attached to it or 

 to floating objects. While the invertebrates indicate plainly that 

 the copper shales were laid down in the sea, the great scarcity of 

 fossils shows that the forms recovered are in the main not in their 

 normal habitat. It appears that only 3 species (the invertebrates 

 cited) were able to adapt themselves to the peculiar conditions of 

 the copper-depositing seas. Not a single scavenging animal is 

 found, and the fact that so many fishes (17 species) were present 

 as food {PalcEoniscus freiesleheni is often more or less decomposed 

 by sulphur bacteria) indicates that the bottom had no scavengers 

 and that it was not a favorable place for any kind of life. 



Pompeckj has carefully studied the fishes, and as all or most of 

 them are carnivorous (some are shell-feeders) the question is raised : 

 On what could they have fed, since there was so little bottom life? 

 He admits that there may have been present an abundance of soft- 

 bodied and shell-less invertebrates on which they preyed, but finally 

 concludes that it is much more correct to assume that most of the 

 fishes (at least 12 species) were drifted into the sea from the rivers. 

 If they also lived in the sea, it must have been in the oxygenated 

 surface waters or the shallow shore regions. On the other hand, the 

 invertebrates present indicate that nearly all of them fed on micro- 

 scopic plants and animals (no ostracods are present, however) and 

 it is perfectly natural to assume that the surface and sun-lit waters 

 abounded in a varied plankton, as do the seas and oceans of today. 

 It was this world of minute forms, the plankton, that rained into 

 the depths, feeding the sparse brachiopod and molluscan life and 

 the common sulphur bacteria. 



Moreover, it is the abundant surface plankton that in all prob- 

 abihty has furnished most of the bituminous matter, assisted further 



