EELATION OF SPECIES TO GENUS. 473 



characters of the three sub-families into which that distinguished 

 naturalist subdivides the Salmonidse. Look at these vomerine 

 teeth in the young of any of the species that is, as I view it, in 

 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, disappearing altogether, marks the true 

 salmon when adult, the common trout growing up with the den- 

 tition of the generic animal. The primitive type, then, is not 

 lost, as M. Valenciennes seems to have supposed, but is retained 

 in one species at least of the natural family. As with the denti- 

 tion, so with the colorations and proportions : and thus the law 

 of generation 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. 



Fig. 506a. The Colt. 



" 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, movements, attitudes ? 

 Not in the least. Its colour is a rich deep fawn, to be found 

 only amongst the wildej in its proportions 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 



