COAL FORMATION. 



localities. From the calcareous beds, subordinate to these sand- 

 stones, in the environs of Edinburgh, Dr. Hibbert has collected the 

 remains of enormous sauruid fishes, the strong and longitudinally 

 striated teeth of which, as well as the whole osseous system, remind 



Fig. 49. Lower Jaw of the Holopticus Hibberti. 



us of the largest sized reptiles. Fig. 49 represents, very much 

 reduced, a portion of the lower jaw of one of these voracious crea- 

 tures, and Jig. 50 a tooth of the natural size of another species. 

 The limestone in which they are found also 

 contains particular concretions (Jig- 51) which 

 are considered to be the excrement of these 

 animals, and, on this account, called coproliles, 

 (from the Greek, kopros, dung, and lithos, 

 stone). The family of squalae was then 

 represented by the division of cestra'cions, 

 characterized by teeth 

 adapted for grinding, 

 (_/?#. 52); and by that 

 of the hybodons, with 

 conoidal but not tren- 

 chant teeth, the ena- 

 mel of which is plaited 

 on both surfaces (Jig. 

 53). The true sharks, 



Fig. 50. Tooth of the w i tn teetn flattened 

 Mtgahchthys Hibberti. and trenc h ant on the 



edges, (fig. 54), did not then exist, and did not appear until very 

 much later in the creta'ceous formation. 



16. Other fishes are found in the coal-basins of the continent 

 of Europe, either in the bituminous schists, as at Sarrebruck and 

 at Antun, or in kidney-shaped masses of carbonate of iron, as at 

 Saint-Etienne. They belong to neighboring genera of sturgeons, 

 named by M. Agassiz palsconi' scus, (Jig. 56), and am'blipterus, 

 and seem to have lived in fresh water. 



Fig. 51. Coprolilfs. 



15. What animal remains are found in the coal-measures? What ire 

 coprolites 1 



16. Are any other fishes fc'ind in coai-beds ? 



