245 
[Annual Meeting. 
the almost exclusively educational work of our Museum and of the 
Teachers’ School of Science, does not at once strike a person, ow- 
ing to the fact that such gardens are usually looked upon as serv- 
ing more for the amusement than the instruction of the public. 
It is, however, perfectly feasible to establish a series of Natural 
History Gardens which shall cooperate with the Museum and other 
public work of the Society, and to form, perhaps, the most effect- 
ive apparatus for public culture in natural history that has ever 
been planned before for any city in the world. 
The connection between our work in the Museum and the pro- 
posed Gardens may be indicated by the following examples : 
The introductory collection, now in course of preparation in the 
vestibule, will show, and in part now shows, the correlative char- 
acter of all phases in the history and structure of the earth and 
what we have called its products, meaning thereby every inanimate 
and animate object. Among these relations there are certain cor- 
relations between the structures of organisms and the four different 
environments in which they live, namely, the salt waters, the fresh 
waters, the dry lands and the air. These correlations are neither 
so indefinite that they can be regarded as useless, nor so obvious 
that they can be neglected with impunity in any general work on 
animals, and yet a library of text books would hardly furnish any 
information of consequence upon this subject. The universal sim- 
ilarity, usually alluded to as analogy, between the organs of sup- 
port or wings of aerial animals, whether mammals, birds, reptiles, 
fishes or insects, is a case in point. Though often cited in text 
books, I have failed in finding any adequate treatment of even 
these obvious facts and usually only very fragmentary mention of 
other structural correlations common in flying animals. 
There is also a distinct tendency to similarity in the conforma- 
tion of organs of support and motion in aquatic animals which can 
be illustrated more effectively in some respects with living exam- 
ples than with lifeless specimens. The Cetacea, Sireniaand seals, 
whose proximate ancestors must have been terrestrial animals, can 
be used very effectively for such an exposition. In becoming suited 
to an aquatic life, they have still retained their air-breathing or- 
gans ; in the Cetacea a fish-like form and propeller-like tail have 
been acquired. In the Sirenia similar changes, though in some 
respects less extensive, have taken place, whereas in the seals the 
position of the hind limbs and their modifications and effective use 
