rOSSIL FISHES. 203 



Fishes. The inaccessible recesses of the waters they in- 

 habit, renders the study of their nature and habits much 

 more difficult than that of terrestrial animals. The arrange- 

 ment of this large and important class of Vertebrata was 

 the last great work undertaken by Cuvier, not long before 

 his lamented death, and nearly eight thousand species of 

 living Fishes had come under his observation. The full de- 

 velopement of their history and numbers, and of the func- 

 tions they discharge in the economy of nature, he has left 

 to his able successors. 



The fact of the formation of so large a portion of the 

 surface of the earth beneath the water, would lead us to ex- 

 pect traces of the former existence of Fishes, wherever we 

 have the remains of aquatic MoUusca, Articulata, and Ra- 

 diata. Although a few remarkable places have long been 

 celebrated as the repositories of fossil Fishes, even of these 

 there are some, whose geological relations have scarcely 

 yet been ascertained, while the nature of their Fishes re- 

 mains in still greater obscurity.* 



cast in the British Museum, taken from another slab found in the same 

 quarries, and impressed with footsteps of some small aquatic Reptile. 



Some fragments of bones were found in the same quarries with these foot- 

 steps, but were destroyed. 



A thin deposite of Green Marl, whieh lay upon the inferior bed of sand, 

 at the time when the footsteps were impressed, causes the slabs above and 

 below it to part readily, and exhibit the casts that were formed by the upper 

 sand, in the prints that the animals had made on the lower stratum, through 

 the marl, while soft, and sufficiently tenacious to retain the form of the foot- 

 steps. 



* The most celebrated deposites of fossil Fishes in Europe are the coal 

 formation of Saarbriick, in Lorraine ; the bituminous slate of Mansfcld, in 

 Thuringia ; the calcareous lithographic slate of Solenhofen ; the compact 

 blue slate of Claris; the limestone of Monte Bolca, near Verona ; the marl- 

 stone of Oeningen, in Switzerland; and of Aix, in Provence. 



Every attempt that has yet been made at a systematic arrangement of 

 these Fishes has been more or less defective, from an endeavour to ar- 

 range them under existing genera and families. The imperfection of 

 .his own, and of all preceding classifications of Fishes, is admitted by 



