466Q Fishes. 



developed. The vertebrae are 60; there are 32 floating ribs on either 

 side, and the pancreatic coeca, or rather cascal apertures, were 36 ; 

 but, if my notes do not mislead me (and they are not very distinct, 

 having been made more than thirty years ago), I find that the 

 number varied, a circumstance I am disposed to attribute to some 

 error in observation. 



The insect which the salmon and sea trout bring with them from 

 the sea is also found to infest the estuary trout. The skeleton tissue 

 is not so dense as in the common and Leven trout: it may induce 

 zoologists and others interested in Natural History to examine the 

 tables of proportions and measurements which I here annex, if I 

 briefly state my own views on the relation of species to natural family 

 or genus, based partly on these tables, but chiefly on the transcen- 

 dental in anatomy. 



The young of every large natural family, by the law of unity, greatly 

 resemble each other : this extends to all the species, externally and 

 internally. As the young grow the characteristics of subfamily and 

 species predominate over the generic, or rather, many of the latter 

 disappear, leaving some which by their presence mark the species and 

 subfamily. If we apply this to the natural family of the Salmonidae, 

 a member of which I now describe, we shall find the view, though 

 transcendental and abstract, fully supported by an appeal to the 

 material manifestations of forms, and fully supporting these proposi- 

 tions : 1st, the specific characters of all the species of any natural 

 family are included in the young of every species of that family ; 

 2nd, the development of any species depends on its position in time 

 and space, and not on the transmutation of one species into another; 

 3rd, were all the species of any natural family destroyed saving one, 

 from that one all the other species belonging to the same natural 

 family might be developed, this being merely a question of time, 

 locality, aud geological influences. 



Thus no species grows out of another; all are foreseen in the 

 natural family or genus, as proved by Embryology and by the Tran- 

 scendental. The following sketch of the natural arrangement of 

 the Salmonidae, extremely imperfect no doubt, is subjoined merely 

 to explain the view. 



Salmonidai. — A Natural Family. 



Generic characters, as exemplified in the young of any of the 

 species : 1st, by the dentition ; 2nd, by the system of coloration — 



