XXX. HUGH MILLER. 



with the other two, our author finds curiously exemplified in 

 the geological history of the fish, which he considers better 

 known than that of any other division of the vertebrata j and 

 he is convinced that it is from a survey of the progress of de- 

 gradation in the great ichthyic division that the standing of 

 the kingly fishes of the earlier periods is to be determined. 



In the earliest vertebrate period, namely, the Silurian, 

 our author shows that the fishes were homologically symme- 

 trical in their organization, as exhibited in the placoids. In 

 the second great ichthyic period, that of the Old Red Sand- 

 stone, he finds the first example in the class of fishes, of mon- 

 strosity hy displacement of parts. In all the ganoids of the 

 period there is the same departure from symmetry as would 

 take place in man if his neck was annihilated, and the arms 

 stuck to the back of the head. In the Coccosteus and Pter- 

 ichthys of the same period he finds the first example of de- 

 gradation through defect^ the former resembling a human 

 monster without hands, and the latter, one without feet. 

 After ages and centuries have passed away, and then after 

 the termination of the Palaeozoic period, a change takes place 

 in the formation of the fish tail. " Other ages and centuries 

 pass away, during which the reptile class attains to its fullest 

 development in point of size, organization, and number ; and 

 then, after the times of the cretaceous deposits have begun, 

 we find yet another remarkable monstrosity of displacement 

 introduced among all the fishes of one very numerous order, 

 and among no inconsiderable proportion of the fishes of ano- 

 ther. In the newly-introduced Ctenoids (AcanthopterygiiJ, 

 and in those families of the Cycloids which Cuvier erected 

 into the order Malacopterygii suh-brachiat% the hinder limbs 

 are brought forward and stuck on to the base of the previously 

 misplaced fore limbs. All the four limbs, by a strange mon- 

 strosity of displacement, are crowded into the place of the 

 extinguished neck. And such, in the present day, is the 



