20 



VERTEBRATE ANIMALS OF THE UNITED STATES 



bony fishes, as the perch and the bass. In some species both types of 

 scales are present, and in some species scales which are intermediate 

 between the two. Certain ganoid fishes, as the garpike, have ganoid 

 scales, which are rhombic in form and are not imbricated, while certain 

 ganoids, as the sturgeon, and certain teleosts, as the sticklebacks, have 

 bony plates on the sides of the body. 



In the description of a fish the average number of scales (Fig. 6) 

 occurring in the lateral line between the head and the caudal fin is 

 given. The number, also, occurring in a dorso- ventral series, between 

 the lateral line and the back and the lateral line and the belly, is 

 usually given. Thus the expression "scales 5-46-11" means that 46 



Fig. 5.- — Scales of fishes: a, ctenoid scale (hinder end of scale at the right); b, ganoid 

 scales; c, cycloid scale (hinder end of scale above) {modified from Cambridge Natural History 

 and Jordan s Guide to the Study of Fishes). 



scales occur in the lateral line, or if no lateral line is present in a lateral 

 series between the head and the caudal fin, that 5 scales occur in a dorso- 

 ventral series between the forward end of the dorsal fin and the lateral 

 line and 1 1 scales between the lateral line and the anus or the forward 

 end of the anal fin. These figures are never absolute for all the indi- 

 viduals of a species, but are liable to vary a sixth from the average 

 given. 



Color. — Fishes are among the brightest of animals. Their colors 

 cover a wide range, and a statement of the markings of a specimen is 

 usually an important part of a description. It must be remembered, 

 however, that there is often a considerable variation in the coloration 

 of a species, that the two sexes are often colored differently, the female 

 being duller than the male, and that bright colors, especially reds and 

 blues, often fade after the death of the animal or when it has lain in a 

 preserving fluid. 



