160 THE PROGRESS OF DEGRADATION. 



after the times of the Cretaceous deposits have begun, we 

 find yet another remarkable monstrosity of displacement in- 

 troduced 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 (Acanthopterygii)^ 

 and in those families of the cycloids which Cuvier erected 

 into the order Malacopterygii sub-^rachiati, the hinder limbs 

 are brought forward, and stuck on to the base of the pre- 

 viously misplaced fore limbs. All the four limbs, by a strange 

 monstrosity of displacement, are crowded into the place o' 

 the extinguished neck. And such, at the present day, is tht 

 prevalent type among fishes. Monstrosity through defect is 

 also found to increase ; so that the snake-like apoday or feet- 

 wanting fishes, form a numerous order, some of whose genera 

 are devoid, as in the common eels and the congers, of only 

 the hinder limbs j while in others, as in the genera Muraena 

 and Synbranchus, both hinder and fore limbs are wanting. 

 In the class of fishes, as fishes now exist, we find many more 

 evidences of the monstrosity which results from both the mis- 

 placement and defect of parts, than in the other three classes 

 of the vertebrata united ; and, knowing their geological his- 

 tory better than that of any of the others, we know, in con- 

 sequence, that the monstrosities did not appear early, but 

 late, and that the progress of the race, as a whole, though it 

 still retains not a few of the higher forms, has been a pro- 

 gress, not of development from the low to the high, but of 

 degradation from the high to the low. 



The reader may mark for himself, in the flounder, plaice, 

 or tiu'bot, — fishes of a family of which there appears no trace 

 in the earlier periods, — an extreme example of the degra- 

 dation of distortion superadded to that of displacement. At 

 a first glance the limbs seem to exhibit merely the amount 

 of natural misarrangement and misorder common to the 

 Acanthopterygii and Sub-hrachiati ; — the bases of the pec- 



