28 
SCANDINAVIAN FISHES. 
The Perch is a fish of such common occurrence, 
that there are probably few persons who require to 
consult a description in order to recognize it. Its body 
is compressed, broadest anteriorly, and covered with 
hard scales, not easy to detach, and rough on account 
of the hooks, as fine as hair, which fringe their outer 
edge and are directed upwards." The head is fairly large/ 
compressed and somewhat pointed: the eyes are of ave- 
rage size/ the jaws of equal length, the nostrils large 
with a double opening, the mouth also large, the jaws, 
the vomer the palatine bones and the pharyngeals co- 
vered with teeth. The back, which is somewhat elevated 
anteriorly, is furnished with two distinct fins. The lateral 
line arched and nearer the back than the belly. The 
first dorsal fin yellowish gray without spots, excepting 
a black spot towards the termination (sometimes at the 
beginning as well): it begins just over the insertion 
of the pectoral fins and ends in a line with the vent. 
The second dorsal fin, the ground colour of which is the j 
same, begins close to the end of the first, and ends a 
little behind the termination of the anal fin. 
The body is grayish yellow, darker towards the 
back, and marked with grayish Mack, transverse bands, 
generally six in number, the middle ones being branched 
at the top and ending in a point at the bottom: the belly 
is white. The colouring of the fish varies greatly ac- 
cording to age and the season of the year, and is also 
considerably affected by the nature of the bottom and 
the composition of the water it inhabits. The young 
specimens are always lighter than the old, their colours 
being dirtier and their coloration less distinct. During 
the spawning season the colouring of the males is brighter 
and more distinct, and becomes still more so in summer, 
the season when the Perch collects in shoals. The spe- 
cimens which live near stony shores and in clear water, 
are alwavs of brighter colour than those which frequent 
places where the bottom is weedy and muddy, and 
thus acquire a faint and sickly colour. In dark, but 
clear water, such as we often see in forest lakes, the 
colouring of the fish is always darker than usual, and 
the inferior fins and the tail are bright red. 
The saccate part of the intestinal canal, or the 
stomach, is comparatively large. The intestinal canal 
forms two curves and has three pyloric appendages 
attached a little below the stomach. The liver consists 
of two lobes, the left one being the larger. The gall- 
bladder is yellow and clear. The male has two milt- 
sacs, but the female only one roe-sac. The air-bladder 
is large, and occupies a considerable part of the ab- 
dominal cavity. The kidneys are placed lengthwise 
below the spinal column. The bladder is saccate. There 
are 20 or 21 ribs on each side, and the vertebras are 
41 or 42 in number. 
The Perch is one of the most widely spread Scan- 
dinavian fishes. It is found at Kilspisj&rvi (lat. 50° N.) 
in Tornea Lappmark, and occurs too in Norway, where 
it is called in some places Tryte. d One may therefore 
assume that, south of the degree of latitude mentioned 
above, it occurs more or less plentifully in all Swedish 
waters. It does not disappear even in lakes that are 
very considerably above the level of the sea. Though it 
often occurs in shallow lakes with a weedy and muddy 
bottom, it thrives best in deep and clear water where 
the bottom is stony, and best of all where there is 
some current. In the sea it occurs oftenest on the 
landward side of the island-belt, and especially at spots 
where a river falls into the sea and diminishes the 
saltness of the water. However, it is also found, 
though more seldom, within the Baltic in the outer 
part of the island-belt where the open sea be- 
gins. It is believed that the Perch thrives best in 
northern latitudes, since it there attains its largest 
a These hooks (spines) are not present in the newly-formed scales, which are cycloid (vid. Winther, Naturh. I'idskr. Kbhvn , 3 R., 
8 B., pp. 28 etc., Plate XVI), but soon become ctenoid, as the margin develops into 1, 3, 5, etc. spines (though the number is not always 
odd), which afterwards become dentoid in substance, and from time to time during their growth become detached at the root, though they 
are still united to the surface of the scale, which continues to grow beneath them. In this way they eventually become fixed to the hind 
margin of the scale, though the fragments of their former roots remain, arranged in rows directed towards the central part of the scale and 
indicating the place, where their development originally began. 
6 In a specimen 3 6 1 /' 0 mm. in length the length of the head is 30 / of the length of the body. Where the length of body is on 
an average 207 mm., the length of the head has proved to be on an average 27.6 % of the length of body, where the length of the body 
is on an average 262 mm., 26.7 %, and where it is 308 mm., 27.5 %. 
c Length of the body on an average 210 mm., longitudinal diameter of the eyes on an average 17.2 % of the length of the head. 
Length of the body on an average 275 mm., longitudinal diameter of the eyes on an average 15.5 % of the length of the head. Length of 
the body on an average 308 mm., longitudinal' diameter of the eyes on an average 14.3 % of the length of the head. 
d Its range in Norway is confined, however, according to Collett, to the northern and southern (not the central) parts. “As is the 
case with several of our fresh-water fishes, it chiefly (or perhaps exclusively) inhabits two extensive districts far apart from each other, na- 
mely the inland parts in the east, south of Dovre, where it has immigrated from Sweden, and Finmark, where it has originally come 
from the north-east”. Coll., 1879, 1. c. 
