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 fisherman finds great difficulty in 
freeing it without 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 body oblong and compressed. Scales of average size and dentated. Two flat spines behind the top 
of the gill-cover. Preoperculum and shoulder-girdle dentated. Inferior margin of the preorbital bone smooth. 
Head covered with scales, except the snout and lower jaw. Car diform teeth of equal size on the intermaxillary 
and maxillary bones, the vomer, the palatine bones and the tongue. Pyloric appendages 4 or 5. Pseudobranchice 
well developed. Branchiostegal membranes separate, each until 7 b 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 with 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 show how closely this genus 
is related to the family of the Sparidae — : by 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- 
culum, which almost disappears along the inferior 
margin of this bone — and some of these American 
species (the sub-genus Morone d ) are of special impor- 
tance in explaining the relationship between the Perch 
and the Pope, two genera so sharply distinct from 
other points of view. Here, within the limits of one 
genus, we have those characters combined, which sepa- 
rate Acerina from Perea. In Boccus {Mo rone) inter - 
ruptus and It. (M.) americanus the two dorsal fins are 
so nearly united, i. e., the fin-membrane from the last 
ray of the first dorsal fin grows 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 anal fin the second spinous ray is the longest and 
strongest as in Acerina, when the latter, as is some- 
times the case, has 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 e , somewhat less 
so in B. 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 body, 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 by 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 way 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 the second dorsal fin, 
the shortness of which in this species is, as far as it 
goes, a token of a lower degree of development. 
a Mitchill Fish. N. Y. (1814). Cuvier called this genus Labrax (Cuv., Val., Hist. Nat. Poiss., 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. Roccus is a barbarous Lati- 
nization of the American ’ Rock-fish '. 
b Rarely 6 or 8. 
c Rarely 13. 
d Gill, ef. Jordan and Gilbert, Syn. Fish. N. Amer., 1. c., p. 530. 
e Cf. Gunther, Brit. Mas. Cat., Fish., I, p. 66. 
