Coloration. 55 



or yellowish, and are, usually, more or less punctulated or 

 spotted. The tail is often lighter in color at the base and 

 outer edge, and dark or dusky between; thus one of the 

 names proposed by Eafinesque for the small-mouth species, 

 — Calliurus punctulatuSj i. e., " dotted painted-tail " — 

 was founded upon the peculiar coloration of the tail of a 

 young bass, his description of the caudal fin being : " base 

 yellow, middle blackish, tip white." Sometimes, however, 

 especially in mature specimens, the tail has a dark border, 

 while the middle is of a lighter tinge ; and often the entire 

 caudal fin will have a uniform coloration. 



■ There are, commonly, several — usually three — dusky 

 or olivaceous streaks along tlie cheeks and gill-covers. 



Inconstancy of coloration is not exceptional with the 

 black bass, for all other genera of fresh water and ana- 

 dromous fishes exhibit this peculiarity in a greater or less 

 degree. Among the causes assigned for the changes in 

 coloration, and which have been either proven true or 

 made tenable by actual experiment and careful observa- 

 tion, are: (1) character of food; (8) condition, depth and 

 temperature of water; (3) color and character of beds 

 of streams, lakes or ponds; (4) atmospheric conditions; 

 (5) age; (6) season of the year; and (7) the changes in- 

 cident to the breeding season; while some assume that 

 (8) the power of changing color is voluntary with some, if 

 not all, fishes. 



Kichard Owen, in "Anatomy of the Vertebrates," 

 says: 



" The varied, and often brilliant colors of fishes, are due to 

 pigment cells at different depths of the skin, but chiefly in the 

 active or differentiating area. Those of silvery or golden luster 

 are mostly on the surface of the scales. The silvery pigment 

 called ' argentine ' is an article of commerce used for the color- 

 ing of fictitious pearls, and offers a crystalline character under 



