CLASSIFICATION BASED ON ANATOMY 133 
most natural arrangements, by attending merely to 
the exterior. The views of such persons are not 
likely to find much favour in the eyes of those who 
have studied animals as organised beings, and who 
do not remain satisfied with inspecting their 
surfaces. Zootomy regards the entire structure of 
animals , which must be examined in all their parts 
before the zoologist can arrange them according to 
their affinities. The study of their interior must in 
fact form the basis of all arrangement; and although 
many natural groups may be formed by attending 
exclusively to the exterior of animals, it is only 
because their internal organisation is presumed to 
be similar. The external parts afford an index to 
the internal; and if we find a bird having a short 
hooked bill and curved claws, we shall not be wrong 
in inferring that it has a wide oesophagus and a 
large membranous stomach. . . . 
“No rational system of ornithology has ever 
appeared, for these two reasons: because no 
system-maker has been equally acquainted with 
the internal structure, the external parts, and the 
habits and actions of birds; and, more especially, 
because birds have not yet been subjected to a 
sufficiently minute examination. I have been 
induced to offer these remarks, because I regret 
that the science has been degraded by having been 
left entirely in the hands of those who appear to 
despise, because they have no knowledge of, the 
internal structure of birds; and I have considered 
it my duty to impress upon the student the neces¬ 
sity of dissecting with all diligence. 
“Were it possible to cast away all the know¬ 
ledge already acquired, and commence anew upon 
the plan of considering birds as admirable 
specimens of divine workmanship, to be examined 
in all their details , we should, I believe, be 
great gainers in real knowledge/’ 
i 2 
