200 Evolution and Distribution of Fishes 



f Strobilodus giganteus, 



E. S. N. K. 

 f Strobilodus siievicus, N. 

 f Liodesmus gracilis, 



K. Z. E. 

 f Liodesmus sprattiformis, S. 

 f Eurycormus speciosus, 



K. E. N. 

 f Callopterus agassizi, K. S. 

 f Oligopleurus cyprinoides, 



K. C. 

 f Oenoscopus esocinus, K. 

 f Macrorhipis muensteri, 



K. 

 f Macrorhipis striatissima, 



K. 

 f Aethalion blainvillei, E. 

 f Aethalion crassus, E. 

 f Aethalion tenuis. 

 Fam. Amiadae. 

 f Megalurus altivelis. 

 f Megalurus brevicostatus, 



K. 

 f Megalurus eiegantissimus. 

 f Megalurus elongatus. 

 f Megalurus grandis, E. 

 f Megalurus grandis, E. 

 f Megalurus lepidotus. 

 f Megalurus polyspondylus, 



f Lophiurus minutus, E. 

 Order Pycnodontidae. 



f Gyrodus hexagonus, S. 

 (frequent.) 

 Gyrodus macro pthalmus, 



K. E. 

 Gyrodus platurus, S. 

 Gyrodus rugosus, K. S. N. 

 Gyrodus titanius, 



K. S. D. N. 

 Microdon elegans, K. S. 

 f-m Mesodon heckeli, S. 

 f-m Mesodon macropterus, 



E. C. 

 f-m Mesodon pulchellus, E. 

 m Mesturus verrucosus, K. E. 

 Teleostei 



f Leptolepis knorri, E. S. 

 (frequent.) 

 Leptolepis macrolepidotus, 



S. 

 Leptolepis polyspondylus, 



E. S. C. 

 Leptolepis sprattiformis, 



E. S. N. 

 Thrissops formosus, K. E. 

 Thrissops propterus, E. 

 Thrissops salmoneus, 



K. E. S. D. C. 

 Thrissops subovatus, K. 



f 



The above includes a larger number of species than is 

 known from all of the other beds of the Jurassic system. 

 But as directly bearing on our present study, we may now 

 inquire as to which of these were probably freshwater and 

 which marine. In the above list the former are prefixed, 

 according to the present writer's views, by (f) before each 

 species or before each genus or larger group, if these are 

 all considered to be such; and by (m) before the latter. 

 This determination is based most largely on statistics and 

 evidence set forth in later chapters of this work, where 

 the groups and genera are specially treated. In part also 

 it is based on evidence furnished by the mass of associated 

 organisms that uniformly occur together. 



On such a basis, and viewing the Jurassic as a whole, 

 we would regard as freshwater beds considerable strata 

 of the Lower and Upper Lias, of the Stonesfield slates, of 

 the Kimmeridgean, of the Portlandian to a less degree, and 

 of the Purbeck. With Woodward's "Museum" volumes 

 as an aid then, it seems that of freshwater species sixty 



