LZ 
Aquatic Lite 
into the invertebrata. 
In considering the anatomy or mor- 
phology of fishes, it is well to select a 
typical bony, or, as an_ ichthyologist 
would say, a typical teleostean form, 
from the center of some average group. 
For this purpose the common perch has 
long been the favorite form employed to 
meet this demand, not only in_ this 
country, but in other parts of the world. 
As will be seen in my photograph of the 
common yellow perch of our waters, re- 
produced as a cut to the present article, 
this species, in the matter of form and 
fins, very perfectly strikes the average 
teleostean fish; this also applies to its 
skeleton and to other parts of its an- 
atomy. Particularly is the perch’s skele- 
ton the standard for ichthyan osteology 
in text books and popular works on 
fishes throughout the literature of the 
subject. 
Apart from the special students of 
fishes, who have gone over some of the 
literature referring to them, there are 
few who appreciate how very old the 
study really is. The fact that it com- 
menced far, far back in history, about 
the time when men began to interest 
themselves in other departments of na- 
tural history, goes without the saying. 
Perhaps of all the zoological writers, 
Aristotle stands among the very earliest, 
and he flourished nearly 2300 years ago. 
Think of a writer on fishes twenty-three 
hundred years ago, that possesses a very 
general and more or less accurate knowl- 
edge of the anatomy and distribution of 
such forms! Not only was Aristotle fa- 
miliar with some 115 fishes found in the 
Agean Sea, but he had described them 
specifically, and studied their morphol- 
ogy. Unfortunately he possessed very 
hazy ideas in regard to specific defini- 
tions; and he accepted, on the whole, the 
names of many of those fishes that had 
been bestowed upon them by the fisher- 
men of that region. As a consequence, 
it is now difficult to determine the species 
to which he referred in his works. Then, 
too, he frequently applied different spe- 
cific names to the same fish at various 
stages of its growth, and when one comes 
to think that Aristotle used only the ver- 
nacular names in nearly all instances, it 1s 
plain to be seen how slender the chances 
are that we shall ever ascertain to which 
species he refers in any particular in- 
stance. 
On the other hand, this ancient ichthy- 
ologist was remarkably accurate in such 
matters as referred to the habits of the 
fish he described; their different modes 
of propagation; migrations, economic 
values, and so on. When we come to 
consult this writer’s works on fishes, we 
soon discover that he recognized the fact 
that such cetaceans as the whales and 
their allies were mammalalian forms and 
not fishes at all; that the former pos- 
sessed lungs and mamme, while true 
fishes had flns and branchiae. He knew 
that Muraena lacked fins, and that eels 
had but two of them. He knew further 
that the cartilaginous fishes, such as the 
sharks and dog fishes, possessed no oper- 
culum, but that nearly all true teleo- 
stean fishes had those bones on the side 
of the head to re-enforce the gill-slits and 
protect the branchiae. 
Aristotle also pointed out that all fishes 
were hairless and featherless; that most 
of them were scaled, while others had 
only a smooth, or in some instances, a 
rough skin. He described the tongue of 
ordinary fishes correctly, and_ stated 
further that fishes never had eyelids. He 
knew that they used their entire body 
when swimming, and that ordinary fish- 
es, or indeed any fish, ever had ears or 
structures that might be called nostrils. 
Fishes possess red arterial blood, and 
enjoy the senses of hearing, smelling 
and tasting. While they lack a urinary 
