7(i6 



SCANDINAVIAN FISHIvS. 



The gill-rakers in the outer row on the first branchial 

 arch are 10 in number, flat at the ti[), and divided into 

 two or three digitate branches. The pharyngeal teeth 

 (fig. 190) are set, as mentioned above, in two rows, 5, 

 as a rule, in the inner row, and 3 smaller tcetli in the 

 outer one. During tiie shedding of the teeth, however, 

 these numbers are altered, and we find, on the one 

 hand, new and more or less undeveloped teeth (at first 

 cucullate), Iving loose in the gums oi- lieginiiing 

 to fix themselves, and uu the other hand, old teeth 

 more or less completely detached from their alveoli. 

 The masticatory surface of the largest (middle and 

 posterior) teetli in the inner row does not become quite 

 distinct until the fish has attained some considerable 

 size. The front tooth in this row (as well as the first, 

 the two first, or even all tiirce teeth in the outer and 

 smaller row) is straigiiter and conical or cylindrical, 

 the remaining teeth l)eing hooked at tlie tip. 



The dorsal fin begins at a distance from the tip 

 of the snout that in young specimens measures about 

 48 or 49 % of the length of the liody, in old 50 or 

 .51 % thereof. Its origin generally lies above the middle 

 of the insertions of the ventral fins; Ijut on examining 

 a number of specimens we find a variation even in this 

 respect. The height of this fin is greater than its length, 

 the former measuring on an average 18 — 16 % of the 

 length of the body, and the length of its base 11 or 

 12 % of the same. The margin is obliquely truncate, 

 with more or less rounded corners, at least in front; 

 and the fin leans slightly backwards. The beginning 

 of the anal fin lies at a, distance from the ti]) of the 

 snout that in young specimens and the males varies 

 between 60 and 65 %, in the females between about 

 67 and 68 % of the lengtli of the body, though this 

 measurement is also subject to individual variations. 

 The height of the fin varies between 13 and 15 % of 

 the length of the body, the length of its base between 

 10 and 12 * of the same. When it is folded, the mar- 

 gin is deeply concave; when expanded, almost straight, 

 though even then the concavity is quite perceptible. 

 The length of the rays in proportion to each other is 

 usually such that the tips of the third and fourth rays, 

 which are the longest, extend to the tip of the last ray, 

 when the fin is completely folded. The caudal fin is 

 forked, with pointed cornei's, the lower lobe being 

 hardly any longer than the u])j)er. The length of the 

 middle caudal rays occupies in young specimens about 

 12—10 % of that of the body, in old about 8—7 a, 



thereof, and measures in the former about ' .,, in the 

 latter about ^ -, of that of the longest rays in the fin. 



The pectoral fins are of oblong shape, with rounded 

 tip when laid back; their length varies between about 

 17\ and 15 96 of that of the body. The ventral fins 

 are broader and more rounded. The distance between 

 the latter fins and the tip of the snout measures in old 

 specimens aljout 45 or 46 %, in -vouiig specimens ali<jut 

 43 %, of tiie length of the l)ody, the distance between 

 the foremost point in tiieir insertions and the corre- 

 sponding point in the insertions of the pectoral fins 

 (the preabdominal length) in old specimens about 23 or 

 24 96, in young about 21 or 22 %, of the same length, 

 and the distance bet\\een the former point and the be- 

 ginning of the anal fin (the postabdominal length) in 

 old specimens about 21 — 24 %, in )oung about 18 %, 

 of the same. The length of the ventral fins themselves 

 is about 13' ;,— 14'/, % of that of the body. 



The scales are of the same shape as in the pi-e- 

 ceding species, but their texture is somewhat firmer, 

 with denser and coarser radiating grooves, which render 

 their hind margin more distinctly crenulated. The la- 

 teral line, whicli slopes slightly at first, runs almost 

 parallel to the ventral margin, and lies much nearer to 

 the belh" than to the back. It contains in most cases 

 about 57 scales, the greatest number in any Scandi- 

 navian Leuciscus. Above the lateral line there are 8 

 or 9 rows of scales, and below it 4 or 5, I'ounting 

 from the dorsal and ventral fins to the lateral line, and 

 excluding the scales of the line itself. Ketween the vent 

 and the lateral line there are 5 or 6 rows of scales* 



It is only during the spawning-season that any ex- 

 ternal difference between the sexes can easily be dis- 

 tinguisiied. During this period the scales of the male 

 are furnished with a rim, consisting of a ro^v of clear, 

 yellowish, ^•errucose tubercles, with dark tip, ■which are 

 wanting in the female, and disapjiear as soon as the 

 spawning is over. 



The coloration of tiie Ide is subject to considerable 

 variations; but the most striking alteration in its dress d' 

 pends on the time of year. In spr'nir/ the Ide weai 

 its spawning-dress, and the prevailing ground-colour is 

 brassy veilow, which gleams through the green pigment 

 wherewith the scales, especially at their insertions, are 

 coated. This pigment grows darker towards the back, 

 which is almost plain grayish green, and lighter, gra- 

 duail)" disai>pearing, towai'ds the bell)-. The head is 

 above of the same colour as the liack, but somewhat 





