396 Classification of Mammah^ Birds, Reptiles and Fishes, 



phosis ; but it has not yet occurred to naturalists to take this meta- 

 morphosis as the regulating principle of classification, to arrange 

 genera according to their agreement with certain degrees of develop- 

 ment, in the natural order of chansfes which the hiorher of these ani- 

 mals undergo. Now, it is my firm belief, that such a new principle 

 can be introduced into our science ; that methodical arrangement 

 may be carried into the most minute details, without leaving any 

 room for arbitrary decision. Proteus, Menobranchus, Amphiuma, 

 Triton, Salamandra, will hereafter have a natural place in our classi- 

 fication, which will be commanded by embryology, and no longer be 

 left to a vague feeling, that aquatic animals are lower than amphi- 

 bious and terrestrial ones, and that the retaining of the gills indicates 

 a lower position than their disappearance. 



Of course, in the outset, we do not find sufficient data to trace 

 this arrangement throughout the animal kingdom, and to make the 

 principle which I have just mentioned the ruling law of classical 

 arrangement. But until such sufficient knowledge is acquired, let 

 me shew that my principle does in fact apply to all classes of the 

 animal kingdom, and will at once contribute to improve all their 

 subdivisions. Among Mammalia, for example, we shall continue to 

 give the aquatic carnivorous animals a lower position among Garni- 

 vera, but no longer simply because they are aquatic, but because 

 they are web-footed, as the web-foot is the earlier form of the limbs 

 in all mammaha whose embryonic development has been traced. 

 We shall be led, for similar reasons, to deny the Bats the high posi- 

 tion which has been assigned to them, and to combine them closer 

 with the Insectivora. We shall separate the Manatees from their 

 present relations, and combine them with tapirs, elephants, &c., as 

 they are rather web-footed Pachyderms, than true Cetaceans. 



Among birds we shall also avail ourselves of the discovery I made 

 last year, that embryos of birds have web -feet and web-wings, and 

 no longer consider Palmipedes as forming a natural group by them- 

 selves, but allow the possibility of having several natural groups of 

 birds, beginning each with web-footed forms. Every one who is con- 

 versant with the natural history of birds, must have been struck 

 with the great diversity of features in birds united in our systems 

 under the head of Palmipedes. Taking all birds together, we hardly 

 notice among them greater differences than those which exist be- 

 tween the various families of Palmipedes, which are, confessedly, 

 brought together upon no other character than the webbed form 

 of their feet ; though among them we have birds of prey, such as 

 the gulls, and others, which seem to stand by themselves uncon- 

 nected, and without any analogy with any other family, such as the 

 swans, geese, and ducks ; and again, the pelicans and the genera 

 allied to them, and also the divers. It can hardly be understood 

 why birds so widely different should be brought together ; and, 

 indeed, their reunion would long ago have been given up, had it not 

 been for the difficulty of finding characters to separate them, and for 



