250 Evolution and Distribution of Fishes 



Es ist wenigstens auffallend, das auch in andern Tertiarbeck- 

 en, wie, z, b, in dem Mittelrheinischen, dass die Gegenden 

 von Frankfurt, Mainz und Wiesbaden umfasst, der reine 

 Thon meist nur Fische, dagegen der Mergel und die derber- 

 en Kalksteine Saugethiere umschliessen. In Bohmer wo die 

 schieferigen Thone theilweise durch den Polierschiefer und 

 Halbopal vertreten werden, ist aehnliches der FalL" 



But Meyer groups together and compares in bewilder- 

 ing manner, sets of teleost fishes that undoubtedly were then 

 freshwater, such as cyprinoid and percoid types, with others 

 like Chipea, Smerdis and Solea that were now fully es- 

 tablished as marine fishes. Explanation we believe is got 

 when comparison is made of Meyer's statements and results 

 with those given in an earlier paper by Eser of Ulm 

 {186:2^^). He carefully classifies, toward the end of 

 his paper, the entire series of rocks exposed, and one 

 then clearly sees that those numbered 1-6 a,b,c, are fresh- 

 water, and correspond to those numbered 1-8 by Meyer. 

 But the stratum 6d of Eser, or 9 of Meyer is as clearly a 

 temporary marine intrusion. For alongside Chipea^ Smerdis 

 and other marine fish remains the molluscan genus Cardium 

 is quoted. Below this a freshwater fauna and flora again 

 appears as Eser's stratum 7 or as Meyer's 10. The writer 

 suspects that a similar explanation may attach to the beds 

 of Aix and of Margarethen. 



In Sauvage's paper {i8j: 171) on the freshwater fishes 

 of Menat in Auvergne, that belong possibly to the same, or 

 to a nearly coeval date as those of Oeningen and Ronzon, 

 he remarks as follows regarding the environment, and 

 probable mode of preservation: These lignitic beds "ac- 

 cumulated in the hollow depressions of the mica schists, and 

 there formed a little pool, around which there developed 

 a luxuriant vegetation. Little by little the clay torn from 

 the surrounding rocks by torrential rains, and the debris 

 furnished by the plants which grew on the margins, had 

 raised the depth of the basin, and owing to the foreign 

 material and to the evaporation which is effected in the 

 dry season, the pool was at length reduced to dryness. It 

 was then that the leaves and the insects fell from the 

 surrounding trees, likewise that the fishes which lived in 



