152 PICTURESQUE SKETCHES 



smaller size, and belonging to another order. They 

 are also so completely enclosed in coats of mail, 

 that their perfect form is handed down as frequently 

 as the teeth and spines of the others. A fish called 

 Dapedius,* from the regular manner in which the 

 large scales are arranged, like a paved surface, on 

 the back, is exceedingly common in the lias in 

 some parts of England, and must have been very 

 abundant. It had a wide, flat, and broad body, 

 covered with large, regular, and nearly square scales, 

 coated with enamel, and a regularly formed tail, 

 of which the scales were oblong ; but one of its most 

 striking peculiarities consisted in the form of the 

 bones of the head, the jaws being short, and the 

 lower one broad, and almost as high as long, while its 

 fore part was depressed towards the middle, to re- 

 ceive the upper jaw. These and the other bones of 

 the mouth, and the whole of the palate, were thickly 

 covered with many successive rows of teeth, gra- 

 dually becoming smaller as they receded within the 

 cavity of the mouth. All the external bones of the 

 head were thickly coated with hard and bright ena- 

 mel strongly marked with granulations. These bones 

 were quite naked, neither flesh nor skin being needed 

 for a surface so defended. 



Besides a large number of species of this and 

 a closely allied genus (Tetragonolepis^}, there were 

 many others also provided with enamelled scales, and 

 a good number of representatives of the family of 

 sauroid fish, although the latter did not attain the 



* AaTTfcW (dapedon), a pavement. 



*f* From the shape of the scales : <nr^a,yuvas (tetragonos) , quadrangular; 

 (/.epis), a scale. 



