154 
ZOOLOGY. 
The mud-fish of Western and Southern waters {Amta 
calva) is a connecting link between the Ganoids and com- 
mon or bony fishes. It bears a general resemblance to and 
is about the size of a bass. Its tail is less ^Mieterocercal 
than that of the garpike^ and thus it comes nearer to the 
bony fishes. 
Sub-Class III. — Teleostei {Bony Fishes, Perch, Cod, etc.) 
These are our common fishes, of which there are nearly 
ten thousand species. The bones are small and exceedingly 
numerous, a number of small bones forming tlie skull and 
Fig, 198.— ADatomj of the Cunner, male. L, lateral line; Jff, heart; Ps, pseudo- 
branchia; /S^p, spleen: 5^, air-bladder; Ki, Ki\ kidney; bl, bladder; T, testis; 
^, aorta; B, brain; In, intestine; Li, liver; G, gills. Drawn by C. S. Minot. 
supporting the fins, so that we may in a single fish count 
upwards of five hundred separate bones. In these fishes 
there are four gills on each side, the single gill-opening 
being covered with a lid or oj^erculum composed of four 
thin bones. 
We would advise the student to dissect a perch, smelt, or any fish, 
with the aid of the following description of the anatomy of the sea- 
perch, which closely resembles the fi-esh-water perch. With a pair 
of forceps, sharp scissors and knife the student, by the exercise of 
care, may make a very fair dissection. 
To dissect a perch the side-wall of the mouth must be removed, 
then the gill-cover ; study the arrangement of the gills. Next make 
