PERCA FLUVIATILIS. 25 



length of its own base, and begins just over tbe spinous extremity of the 

 opercular bone. The fin rays are strong, pointed, thirteen to fifteen in number. 

 The last ray is very short, and the fifth is highest, and equal to two-fifths 

 the height of the body. The second dorsal fin is only a little less elevated ; 

 its base measures two-thirds the length of that of the first dorsal fin. Its 

 first spinous ray is very short, and is united to the first dorsal by membrane. 



The anal fin commences beneath the anterior half of the second dorsal. 

 Its two strong spinous rays are less elongated than the succeeding soft rays. 



The pectoral fins are moderately developed, and have a rounded outline. 

 The first and last rays are about half the length of the middle and longest 

 rays ; there are fourteen rays in the fin. 



The ventral fins commence below the middle of the pectorals, and are 

 about as long as those fins, but the rays are broader. The fin extends back- 

 ward half-way to the vent. 



The caudal fin is evenly lobed, and only moderately concave in the outline 

 of its hinder margin. This fin forms one-seventh of the length of the Perch. 



o o 



The lateral line is nearly parallel to the back; its length includes from 

 sixty to sixty-eight scales. At the base of the ventral fin there are from thir- 

 teen to fifteen rows of scales below the lateral line, and seven to ni\ie rows of 

 scales above it. The scales are finely serrated at the free edge, are gener- 

 ally broader than long, are largest on the abdomen and the sides, and 

 smallest on the throat. The caudal fin is the only fin with scales at its base. 

 There are three pyloric appendages to the stomach, of moderate size. The 

 air-bladder adheres to the vertebrae and ribs. 



The shade of colour varies from a brassy yellow to a bluish or greenish 

 tinge, becoming whitish on the belly, golden yellow at the sides, and blackish- 

 green on the back. From five to nine brownish-black vertical bands extend 

 down the sides of the Perch between head and tail. These bands vary in 

 length, breadth, and intensity of colour, and are sometimes represented by 

 blackish-clouded spots, or spots and bands may both be absent. The large 

 black spot between the last two or three rays of the first dorsal fin is, how- 

 ever, always present. The first dorsal tin is violet-grey ; the second dorsal has 

 a yellowish base, becoming reddish and green at the borders ; but the colours 

 of the fins vary. The ventral, anal, and caudal may be orange or vermilion, 

 while the pectoral is described by Yarrell as pale brown, by Heckel and Kner 

 as yellowish-red, while Fatio finds it to be yellow. These differences confirm 

 BlanchaixFs statements that the colours of the fins and of the fish vary with the 

 locality and season at which it is taken, and, we might also add, with age. 

 \ arious Continental writers mention a yellow variety, which Siebold considers 

 to resemble the Yellow Perch (P.erca jlavescens) of North America. Cuvier and 



