44 



SCANDINAVIAN FISHES. 



man's only prize. It is a troublesome catch in the net, 

 as in its struggles it becomes very tightly entangled in 

 the meshes, and the lisherman iinds great difficulty in 

 freeing it \\-ithout pricking his fingers with the sharp 

 spines of its fins and gill-cover. 



Its enemies are sufficiently numerous. In addition 

 to the dangers it runs at the hand of man, though a 

 fish of prey itself, it often falls a prey to larger fishes 

 and waterfowl. 



(Ekstrom, Smitt.) 



Genus ROCCUS". 



Form of the ho(h/ ohJonr/ (tiid compressed. Scales of average size and dentated. Two Jiat spines behind the top 

 of the (jUl-cover. Preoperctdum and shoidder-girdle dentated. Inferior margin of the preorbital hone smooth. 

 Head covered ir'dh scales, except the snout and loiver jaw. Cardiform teeth of equal size on the intermaxillary 

 and ma.xillary hones, the vomer, the palatine hones and the tongue. Pyloric appendages 4 or .5. Pseudohranchice 

 irell developed. Branchiostegal memhranes separate, each tvith 7'' rays. Dorsal fins separate or nearly so, the 

 first containing 9 rays. In the anal fin .3 spinous rays; its base shorter than the soft-rayed part of the dorsal. 



Caudal fin tvith 15" branched rays. 



The European Sea-perch is the representative of a 

 genus which is most highly developed in form in North 

 America, where its characters are still more marked 

 and it lives in the same ■way as the Salmon, ascending 

 the rivers to spawn or even landlocked in fresh water. 

 The American species also sllo^v hew closely this genus 

 is related to the fjiinily of the Sparidae — : l^y the 

 greater size of the scales, the deeper form of the body, 

 the greater breadth (depth) of the preorbital bones and 

 the increased fineness of the serration of the preoper- 

 culura, which almost disappears along the inferior 

 margin of this l^one — and some of these American 

 species (the sub-genus Morone'') are of special impor- 

 tance in explaining the relationship between the Perch 

 ;iud tlie Pope, two genera so sharply distinct from 

 other points of view. Here, Avithin the limits of one 

 genus, we have those characters combined, Avhich sepa- 

 rate Acerina from Perca. In Boccus {Morone) inter- 

 ruptus and R. (M.) americanus the two dorsal fins are 

 so nearly united, i. e., the fin-membrane from the last 

 ray of the first dorsal fin groAvs so high on the first 

 ray of the second dorsal fin, that when the first fin 

 is raised, the second also rises simultaneously; and in 

 the an.-il fin the second spinous ray is the longest and 

 strongest as in Acerina, when the latter, as is some- 

 times the cnse, lias three spinous rays in the anal fin. 



Furthermore, in conjunction with these characters so 

 like those of the Pope, the "muciferous ducts" and 

 "muciferous cavities " (see above) of the head are almost 

 as highly developed as in the Pope on the sides of the 

 lower jaw, the preoperculum and the snout. This is 

 most noticeable in Boccus americanus', somewhat less 

 so in R. interruptus and still less in Boccus (Lepibema) 

 chrysops, where, however, as in all the other species 

 of Boccus, they may be discerned exteriorly. The 

 most important difference between these three species 

 of Boccus and the others is the deep shape of the body, 

 the least depth of the tail being about 11 per cent of 

 the length of the Ijody, while in the other it is at 

 most 9,5, at least where the length of the body is 

 not more than 316 mm. This character with several 

 others, to judge b}' the changes of growth known to 

 us in the European Sea-perch, sets them highest on 

 the scale of the generic development. The fourth Ame- 

 rican species, B. lineatus, comes nearest our Sea-perch, 

 and in the same Avay seems to represent the lowest 

 grade of development within the genus, especially in 

 its most remarkable character, the great length of the 

 lower jaw, which is about 15 % of the length of the 

 body and longer than the base of tlie second dorsal fin, 

 the shortness of which in this species is, as far as it 

 goes, a token of a lower degree of development. 



" MlTCHiLL Fish. N. Y. (1814). CuviEit called this genus Labraj- (Cuv., Val., Hist. Nat. Foiss., II, p. 55) though he must have 

 known and observed that this name had already been employed by Pallas to denote a genus of another family. Boccus is a barbarous Lati- 

 nization of the American 'liock-nsh'. 



'' Rarely (! or 8. 



■^ Uarely IH. 



•^ Gill, cf. Johdam and Gilbert, Syn. Fish. N. Amer., 1. c, p. 530. 



' Cf. GOnturr, Brit. Mus. Cat., Fish., I, p. (56. 



