296 



SCANDINAVIAN FISHES. 



The pores belonging to the sj^stem of the lateral line 

 are small, and in old specimens hardly distinguishable. 



The pectoral fins and the disk of the ventral tins 

 are of the same structure and shape as in the preceding 

 genus; but the former are not so broad — their upper 

 angle lying lower do^vn, and the number of rays being 

 oulv 20 — and are without the incision in tlie lower 

 posterior part of tlie margin. The distance between 

 thi' pectoral tins at the bottom is scarcely equal to the 

 diameter of the eye; when laid Ijack, the fins do not 

 extend to the vent, the length of tlieir uppei- part in 

 full-grown specimens being 14 or 15 % (13'8 — I5'l %) 

 of the length of the body. In specimens from the 

 Baltic, however, the length of these fins is relatively 

 greater (17 — 19 %), and also in young specimens: 

 in specimens between 24 and 28 mm. long we have 

 found them to measure 17'5 — 17'8 % of the length of 

 the l)ody. They are also, as a rule, longer in the male 

 than in the female. The length of the oval disk formed 

 by the ventral fins is also relatively greater in A'oung 

 specimens than in old and, generally, in the male than 

 in the female, its longitudinal diameter, including the 

 dermal rim, varying in adult specimens between about 

 14\'o and 19'/2 % of the length of the body, and in voung 

 specimens between 20 and 2172 thereof. In the hind 

 ]iart of the dermal margin we find the tips of the four 

 posterior (inner) rays on each side". In the old males, 

 which are furnished with a genital papilla behind the 

 vent, the latter lies about half-way between the ad- 

 hesive disk and the anal fin; while in young specimens 

 and the females it generallv lies nearer the latter. Hence 

 it follows, as a rule, that the length of the pectoral 

 fins in young specimens and those from the Baltic (see 

 above) is greater than the distance between the vent 

 and the anal fin, but in the adult Atlantic specimens less. 



The first dorsal fin, with from 6 to 8 simple, but 

 soft, spinous rays, is covered in old specimens, as wa 

 have mentioned above, by the more or less cartilaginous 

 huuip\ which develops during growth. This hump 

 generally rises almost evenly from the occiput or forms 



a slight break at its origin; but sometimes, especially 

 in old males, it may rise like a cock's-comb, or at least 

 in a sharply marked semicircle, to a height equal to 

 the depth of the head at the occiput or that of the 

 body at the termination of the abdominal cavity. The 

 alteration in the shape of the liody thus caused is so 

 great tliat Pallas and his successors long Ijelieved that 

 the young specimens were a distinct species {Cyclopteriis 

 minutus, Plate XVI, the three middle figures). Fries 

 Avas the first to demonstrate that these young examples 

 belong to the species now under consideration, in spite 

 of their rounded back and distinct anterior dorsal fin, 

 Avith visible rays'. At this period, before the rows of 

 tubercles appear, the skin is also smooth; and some- 

 times, as V. DuBEN and Koken have shown, specimens 

 30 mm. long may be "entirely smooth and even, with- 

 out the least trace of tubercles, spines or ridges". For 

 a long time, too, the tips of tlie last rays in the first 

 dorsal fin may be distinguished, thougli not with ease; 

 this seems to be most persistent in specimens from 

 the Baltic. 



The second dorsal and the anal fins are very like 

 each other, the first (simple and unarticulated) and the 

 last (articulated and generally simple) rays being the 

 shortest, and the fourth (the first branched) ray the 

 longest. The remainder of the margin is rounded or 

 almost straight. Tlie base of the former fin, the length 

 of which varies betAveeii 15 and 20 % of that of the body, 

 and undergoes greater increase with age, even relatively 

 than the length of the anal fin, is always longer than 

 that of the latter, which varies between about 14 and 

 15',;, % of the length of the body. During youth the 

 height of each of these fins is equal to its base; in 

 old specimens, on the other hand, the height of the 

 anal fin is greater than the length of its base, but in 

 the second dorsal fin the proportions are reversed. 

 Specimens from the Baltic are apparently marked by 

 the still more considerable height of these fins (more 

 than 18 % of the length of the body), and hence it 

 follows that in tlieir case, even in old specimens as 



" According to Bloch (Fische Deutscld., Ill, \<. 104), Hanow estimated tliat tlie adliesive power of the disk in a Lumji Sucker 8 

 Prussian inches (21 cm.) long represents a lifting-power of 74' ._, Zollpfund (34**/jq kgrm.). Pennant states {Brit. ZooL, III, p. 118) as a 

 proof of this power that he once placed a fish of this species, just caught, in a pail containing several gallons of water, and by taking ludd 

 of the tail of the fish was able to lift pail, water and tish without forcing the latter to relinquish its hold of the bottom. It is, however, 

 tlie adhesion of the disk alone, without any special exertion on the part of the fish, that is at work here, for Buceland {Nat. Hist. Brit. 

 Fish., p. 126), on cutting oft" the adhesive disk of a dead Lump Sucker 5 kgrm. in weight, and pressing it against a damp window-sill, 

 found that it was only with the greatest effort he could just lift it straight up, though laterally it did not offer the slightest resistance. 



' A similar formation appears during the spawning-season in the males of the Pacific Salmons. 



' Even Ascanius, however, had seen and identified these young specimens, though his figure of one of them (1. c.) is not verj- instructive. 



