l-' n ZOOLOGY. 



and a dentition identical. The young fish before me was, in 

 fact, a generic animal, including within it the specific charac- 

 ters of all the species composing the natural family. To 

 connect this generic animal with any species, you have but to 

 imagine the disappearance of certain characters then and 

 there present. Nothing requires to be added. Take, for 

 example, the dentition the dentition of the vomer, to which 

 M. Valenciennes attaches so much importance, and in which 

 he has endeavoured to discover the true distinguishing 

 characters of the three sub-families into which that distin- 

 guished naturalist subdivides the SalmonidaB. Look at these 

 vomerine teeth in the young of any of the species that is, as 

 I view it, iii the generic animal, and in the adult of all the 

 species, that is, in the animal specialized and we shall find 

 that the generic animal possesses a dentition embracing all 

 the characters by which the fully-developed individuals are 

 afterwards to be recognised. But it is the young alone which 

 comprises all, combines with the anterior group of teeth (teeth 

 of the chevron) a double row on the body of the vomer, which 

 row, becoming in due time single, characterizes, according to 

 M. Valenciennes, the adult of the sub-family Forelle, or, dis- 

 appearing altogether, marks the true salmon when adult, the 

 common trout growing up with the dentition of the generic 

 animal. The primitive type, then, is not lost, as M. Valen- 

 ciennes seems to have supposed, but is retained in one species 

 at least of the natural family. As with the dentition, so with 

 the coloration and proportions : and thus the law of genera- 

 tion being generic, and not specific, marks the extent of the 

 natural family, its unity in time and space, the fixity of its 

 species, the destruction of some and the appearance of others 

 being but the history, not of successive creations, but of one 

 development, extending through millions of years, countless 

 as the stars of the firmament. 



" Look now at the colt a few months old as it gambols 

 through the fields, and say, does it resemble the domestic 

 animal from which it is sprung, in colour, proportions, move- 

 ments, attitudes? Not in the least. Its colour is a rich 

 deep fawn, to be found only amongst the vilil< : in its pro- 

 portions it resembles the quagga or zebra, and as it canters 

 along, its rocking-horse motion and short frisking tail recal 

 -to the mind scenes only to be seen in Southeni Africa, on the 

 plains of the Koonap, or the slopes of the Winterbergen, 

 where roams the wild horse, to which this young of a do- 



