154 



ZOOLOGY. 



The mud-fish of Western and Southern waters (Amia 

 calm) 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 " heterocercal " 

 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 the skull and 



Fig, 198.— Anatomy of the Cunner. male. L, lateral line; Ht, heart: Ps. pseudo- 

 branehia; Sp. spleen: S, air-bladder: Ki,Ki', kidney; bl, bladder: T. testis; 

 A, 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 operculum composed of four 

 thin bones. 



We would advise tlie student to dissect a perch, smelt, or any fish, 

 with the aid of tlie following description of the anatomy of the sea- 

 perch, which closely resembles the fresh-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-well of the mouth must be removed, 

 then the gill-cover; study the arrangement of the gills. Next make 



