40 TI1K FUK.SH-WATKU FISHES OF EUKOl'K. 



fourth, fifth, and sixth. The later spines decrease in length, so that the 

 last ray is the smallest. The first dorsal fin is often connected by a low 

 membrane with the second dorsal, but three to four rows of scales sometimes 

 separate them. The first spinous ray of the second dorsal fin is slender, and 

 is lower than the succeeding- jointed rays, which at first are as high as 

 the first dorsal, and gradually diminish. Its base is as long as the base of 

 the first dorsal. 'The anal aperture is placed beneath the commencement of 

 the second dorsal fin. The anal fin is placed behind it, and has some of the 

 rays longer than those of the second dorsal. The base of the ventral fin 



Fig. 14. LUCIOPEKCA SANDRA (CTJVIEK). 



is but little behind the base of the pectoral fin; both are of about equal 

 length. 



The caudal fin is equally lobed, and moderately concave, with its terminal 

 rays measuring from one-half to two-thirds of the length of the head. 



The scales on the body are relatively smaller than those of the Perch; 

 but they are equally rough and denticulated, and vary in size and number. 

 The lateral line is parallel to the back; it includes from seventy-five to 

 ninety scales. Above the lateral line are twelve to fourteen rows of smaller 

 scales, and beneath it sixteen to twenty rows of larger scales under the first 

 dorsal ; but at the extremity of the tail there are only four to six rows 

 of scales on each side of the lateral line. The scales are smallest on the throat, 

 abdomen, and fore-part of the back. Usually they become larger towards 

 the tail ; but their size varies with the stream, the Danube yielding large- 

 scaled specimens, while in the streams of Galicia, Northern Russia, and Sweden 

 small-scaled varieties are found. The scales vary a little with age ; in the 

 young the whole of the upper part of the head, the opercular bones, and base 

 of the pectoral fin are, for the most part, without scales ; but with age the 

 operculum, parts of the cheeks, and crown of the head between the eyes, often 

 carry scales; while, with the exception of the first dorsal, all the fins have 



