212 FOSSIL FISHES. 



Fishes in Strata of the Carboniferous Order. 



I select the genus Amblypterus (PI. 27^,) as an example 

 of Fishes whose duration was limited to the early periods 

 of geological Formations ; and which are marked by cha- 

 racters that cease after the deposition of the Magnesian lime- 

 stone. 



This genus occurs only in strata of the Carboniferous or- 

 der, and presents four species at Saarbriick, in Lorraine ;* 

 it is found also in Brazil. The character of the teeth in 

 Amblypterus, and most of the genera of this early epoch, 

 shows the habit of these Fishes to have been to feed on de- 

 cayed sea-weed, and soft animal substances at the bottom 

 of the water : they are all small and numerous, and set close 

 together like a brush. The form of the body, being not cal- 

 culated for rapid progression, accords with this habit. 



The vertebral column continues into the upper lobe of the 

 tail, which is much longer than the lower lobe, and is thus 

 adapted to sustain the body in an inclined position, with the 

 head and mouth nearest to the bottom. 



Among existing cartilaginous Fishes, the vertebral column 

 is prolonged into the upper lobe of the tail of Sturgeons and 

 Sharks: the former of these perform the office of scavengers, 

 to clear the water of impurities, and have no teeth, but feed by 

 means of a soft leather-like mouth, capable of protrusion and 



* The Fishes at Saarbilck arc usually found in balls of clay ironstone, 

 which form nodules in strata of bituminous coal shale. Lord Greenock lias 

 recently discovered many interesting examples of this, and otlier genera of 

 Fishes in the coal formation at N e\v haven, and Wardie, near Leitii. The 

 shore at Ncwhaven is strewed with nodules of ironstone, washed out by the 

 action of the tide, from slialc beds of the coal formation. Many of these 

 ironstones have for their nucleus a fossil Amblypterus, or some other 

 Fish ; and an infinitely greater number contain Coprolites, apparently de- 

 rived from a voracious species of Pygopterus, that preyed upon the smaller 

 Fifibes. 



