4790 Fishes. 



represents a generic type, transcendental, and requiring for its full 

 development or embodiment in all its material, that is, specific forms, 

 countless millions of years; for as the young, that is, the generic ani- 

 mal, includes many species, perhaps all which the natural family can 

 assume in time and space, so as species die out, others appear, new 

 to the world as species, but not generically. The ossemens fossiles 

 belong to species clearly distinct from those that now live ; their 

 generic resemblance is undeniable. Species perish, but not genera, 

 and thus the past, present and future, form but one. Species are 

 not convertible into each other by any influences at present known 

 to man : that these species follow each other, agreeably to certain 

 laws, may be admitted, but that it is in the direction of a supposed 

 perfectibility I do not believe, nor ever did. Time, which means plan 

 and circumstances, which mean the geological changes on the earth, 

 are, no doubt, the producing causes of species. Hence, the generic 

 unity of every natural family, and the appearance from time to time 

 of individuals, not resembling the species from which they spring, 

 but others of the same natural family. 



As regards the dentition, then, of the Salmonidae, the young are 

 of no species ; on the contrary, they are transcendentally generic, 

 that is, each individual, no matter how descended hereditarily, 

 displays all the characters of all the species and subfamilies of that 

 natural family to which it belongs : as it contains within it the 

 possible of all the species, it seems reasonable to believe, that its de- 

 velopment into any peculiar species must be dependent on physical 

 causes at least, which must have a direct relation to the existing order 

 of things. Should a species become extinct, another appears. 

 This implies no new formation or creation, nor after all any real ex- 

 tinction, for the characters of the new species (new to man, who 

 naturally looks only to the adult) and those of the extinct are still 

 included in the young of every species which yet lives, or has lived. 

 What has become extinct, may even reappear; but should the natural 

 family perish all the species cease with it. 



Domesticity plays a limited part in the production of varied forms, 

 but these forms do not constitute species : some species are more in- 

 fluenced by domesticity than others ; man very little, if at all. It is 

 the same as regards the laws of coloration and proportions : the gene- 

 ric animal includes the types of all. 



I have sometimes thought that this law of natural family and of 

 propagation of a generic animal not at first specific may play a part 

 in some phenomena at present inexplicable. For example : all that 



