CLASSIFICATION AND NOMENCLATURE. 7 



aftbrd the most general distinctions ; and attention is also paid 

 to those of the wings ; but in all, the internal organs have been 

 too much neglected. An arrangement may be founded on the 

 variations of any part : — the brain, the heart, the feet, the bill, 

 or the sternum ; but classifications resulting from such partial 

 considerations must be extremely imperfect. As the various 

 organs do not undergo similar or analogous changes in the dif- 

 ferent species, linear series are not capable of connecting them 

 by general affinity. The idea that in a given group, each of 

 its divisions is represented analogically by a corresponding 

 division in another group, is certainly, to some extent, counte- 

 nanced by appearances ; but when it is attempted to be carried 

 through the entire series, it gives rise to the most fanciful and 

 forced substitutions ; such, for example, as that of conceiving 

 a cock to be analagous to a horse, because, as it is alleged, 

 both kick, or to a bull, because its spurs are somewhat similar 

 to horns. In one point of its structure, a species may be 

 allied to another, while in a second point it may resemble 

 a third species. Thus, a Pterocles, or Sand Grouse, resembles 

 the Pigeons in its general form, and in that of its wings, while 

 its feet are similar to those of a Grouse, and its tail not unlike 

 that of some Parrots, as well as of many other birds. In some 

 respects a bird may be very similar to another, while in one 

 or more particulars it may manifest some relation to a species 

 extremely different in everything else. In a linear series, 

 therefore, it is impossible to place species in the order of their 

 affinities ; nor can those of species or genera be exhibited by 

 disposing them in circles, parallel series, quincuncial rows, or 

 any other figures, on a flat surface, that is, in diagrams on 

 paper. To present affinities, species would require to be fixed 

 in empty space, and represented by forms bearing no resem- 

 blance to birds, but having parts more and less elongated, to 

 meet parts of other near and distant species ; so that such an 

 arrangement, were it made by a being v/ho understood all the 

 relations of the species, would, by exhibiting such a multitude 

 of reticulations, be just as unintelligible to us as is the order of 

 things studied in the economy of nature such as we see it. 

 When objects, then, are placed in linear series, whether di- 



