OF CREATION. 149 



been excelled in strength or vigour by any of the 

 Invertebrata. 



The ammonites and belemnites are both so charac- 

 teristic of the lias, and so remarkable in themselves, 

 that they claimed some detailed description in an 

 account of the various groups of animals of that 

 period, no longer existing upon the earth. They 

 seem to have chiefly abounded, or at any rate are 

 most commonly preserved, in those beds of the se- 

 condary epoch which indicate a moderately deep 

 sea with a muddy bottom, and their remains are 

 then so abundant, as to form in some cases complete 

 strata of themselves. They may indeed be said to 

 equal in number the Orthoceratite remains in the 

 older rocks ; but the ammonites were in reality the 

 representatives of these straight but external shells, 

 the belemnites being superadded and of higher organ- 

 ization. 



Besides the fragments of shells, and other remains 

 of invertebrated animals already described, we find 

 also in the lias a very abundant supply of Ichthy- 

 olites,* or fossil remains of fishes of various kinds, 

 the most abundant of them belonging either to a 

 peculiar family of sharks, or to tribes character- 

 ised by their coating of enamelled scale and bone, 

 and the entire absence of true skin. Of the former of 

 these fishes we only find the teeth and the remains 

 of peculiar spines ( (Ichthyodorulites, fig. 56) which 

 had been attached beneath the skin in the flesh; so 

 that there are no very certain grounds by which 



(iclithys), a fish ; \iQog (lithos, unde lite), a stone. The ter- 

 mination lite is constantly made use of in Geology to indicate a fossil body. 

 f See ante, p. 100. 



