PROGRESS OF ICHTHYOLOGY. 409 



decide. But judging, as I have already said, from 

 the general analogy of the natural sciences, I find it 

 difficult to conceive that the ichthyological method 

 of M. Agassiz, recently propounded with an especial 

 reference to fossil fishes, can be otherwise than an 

 artificial method. It is founded entirely on one 

 part of the animal, its scaly covering, and even on 

 a single scale. It does not conform to that which 

 almost all systematic ichthyologists hitherto have 

 considered as a permanent natural distinction of a 

 high order ; the distinction of bony and cartilagi- 

 nous fishes ; for it is stated that each order contains 

 examples of both 15 . I do not know what general 

 anatomical or physiological truths it brings into 

 view; but they ought to be very important and 

 striking ones, to entitle them to supersede those 

 which led Cuvier to his system. To this I may add, 

 that the new ichthyological classification does not 

 seem to form, as we should expect that any great 

 advance towards a natural system would form, a 

 connected sequel to the past history of ichthyology ; 

 a step to which anterior discoveries and improve- 

 ments have led, and in which they are retained. 



But notwithstanding these considerations, the 

 method of M. Agassiz has probably very great 

 advantages for his purpose ; for in the case of fossil 

 fish, the parts which are the basis of his system 

 often remain, when even the skeleton is gone. And 

 we may here again refer to a principle of the classi- 



15 Dr. Buckland's Bridgewaler Treatise, p. 270. 



