ANATOMY OF THE CUNNER. 431 
Subclass 3. Teleostei (Bony jishes).—We now come to a 
type of fishes which, within very recent geological times as 
well as during the present period, has become differentiated 
or broken up into thousands of species, corresponding to 
the complexity of their physical environment as compared 
with the simple features of the physical geography of De- 
vonian and Carboniferous land-masses. Like most of the 
jarger groups of animals, as the Decapod Crustacea, and 
especially the insects, as well as the mollusks, the bony 
fishes have attained an astonishing amount of specialization, 
as if the tree of icthyic life, taking root m the Silurian Age, 
and sending out but a few branches in later Paleozoic times, 
had suddenly, in the Cretaceous and Tertiary Ages, thrown 
out a multitude of fine branches and twigs intertwining and 
spreading out in a way most baffling to the systematist. 
The essential, diagnostic characters of the bony fishes, i.¢., 
such as separate them from the Elasmobranchs and Ganoids, 
are as follows: The skeleton is bony, the vertebrae being sep- 
arate ; the outer elements of the scapular arch are simple, the 
inner elements for the most part bony and usually three or 
two in number ; the pectoral fins are without any bone rep- 
resenting the humerus, and are connected with the scapular 
arch by several (generally four) narrow bones (Gill). The 
optic nerves cross one another. The gills are free, usually 
four on each side, and with several opercular bones. The 
heart is without a cone, but with an arterial bulb, and with 
but two valves at the origin of the aorta. The intestine is 
destitute of a spiral valve. 
The student should dissect a typical Teleost, such as a 
fresh-water or sea perch, with the aid of the following ac- 
count of its anatomy. The drawing and account here given 
of the anatomy of the sea-perch have been prepared by Dr. 
€. Sedgwick Minot. The common sea-perch or cunner 
(Tautogolabrus adspersus Gill, Fig. 396) resembles the fresh- 
water perch very closely in its anatomy, the most note- 
worthy difference being the absence of the ceca at the 
pyloric end of the stomach in the marine species; with this 
exception the following description applies almost equally 
well to the fresh-water perch, so that this account will be 
