with the commencement of the Chalk. The Squaloids or 

 true Sharks commence with the Cretaceous formation, 

 and extend through the Tertiary strata up to the present 

 time. In these successions, we see, in the clearest manner, 

 the wisdom and the true knowledge of the Creator, who 

 in the beginning laid down, as it were, certain fixed laws 

 for the government and well-being of his creatures, and 

 pre-ordained that certain oflGices or processes should be 

 constantly in progress, to prevent the too rapid increase of 

 particular tribes of beings, or for the purpose of cleansing 

 the waters of accumulated vegetable substances, which it 

 was necessary to remove, to prevent their proving injurious. 

 But though these various offices were constantly going on 

 at different epochs, it has been by the aid of different 

 agents, each making way for its successor, perhaps better 

 adapted by organization for the especial purpose than the 

 preceding. 



Of the Ganoidians, the first which claims our attention 

 is the Sauroid Family, consisting of those insatiable lizard- 

 like fishes, which possess highly important characters, com- 

 bining those of the reptile and the fish. Seventeen genera of 

 Saurian Fishes have been discovered fossil, while they have 

 only two living representatives, — the genera Lepidosteus, 

 inhabiting the fresh -waters of America; and the Polypteris, 

 the Nile and rivers of Senegal. The largest fishes yet disco- 

 vered of the Ganoid order belong to the genus Megalichthys, 

 which appear to have been extensively distributed through the 

 Coal Fields of Great Britain, more especially in the cannel or 

 stone Coal ; — the first examples, and also the most celebrated 

 and unique, being the nearly perfect head and portion of the 

 body of MegaUchthys Hibberti, from Low Moor, deposited 

 in the Museum of the Leeds Philosophical Society in 1823. 

 Subsequently a smaller head was found at the Waterloo Col- 

 liery, which is also in the same Museum ; since which period 

 numerous scales and teeth have been detected at Middleton 



