COMMON FLOUNDER. 
401 
shape as in the Plaice, and its length in our specimens 
varies between 19 and 23 % of that of the rest of the 
body; but the number of the branched rays has con- 
stantly proved to be no more than 12. Vent and anal 
spine as in the Plaice. The former, however, is com- 
paratively large, and is furnished on the eye side with a 
urogenital papilla, which in the specimens examined by 
us has generally seemed to be better developed than 
in the other species of the genus. 
In order to account for the external relations be- 
tween the Plaice and the Flounder, and to give the 
most important changes of growth in the two species 
— excluding their earliest stages — we here append the 
following table of averages: 
Average in 
Pl. platessa. 
PI. fiesus. 
Length of the body expressed in millimetres.- 
257 
3G5 
251 
295 
Length of the head in % of the length of the body 
22.9 
23.3 
23.0 
25.5 
Greatest depth of the body ,, „ ,, „ ,, 
39.7 
42.fi 
41.o 
41.3 
Least 
7.8 
8.o 
7.7 
7.3 
Postorbital length of the head , ,, ,, ,, ,, ,, ,, 
15.3 
15.9 
15.o 
16.8 
Length of the head.. in % of the greatest depth of the bodv 
57.7 
54.8 
57.8 
59.5 
Postorbital length of the head ,, ,, ,, ,, „ „ ,, 
38.3 
37. g 
38.5 
40.8 
Length of the branch of the lower jaw on the blind side in % of the length of the body 
8.i 
8.5 
8.4 
8.7 
„ „ „ „ „ „ „ „ „ „ eye „ ,, ,, „ „ „ „ „ „ 
7.n 
7.7 
7.9 
8.i 
,, „ base of the dorsal tin ,, „ „ „ ,, ,, „ ,, 
G9.c 
1)9.3 
67.3 
66.2 
„ „ „ „ „ „ anal „ - - „ „ ,, „ „ „ „ „ 
53.2 
53.2 
47.o 
45.9 
„ „ „ longest ray of the dorsal tiu „ ,, „ „ „ „ ,, „ 
11.2 
11.5 
12.o 
12.1 
,, ,, ,, .. „ anal 
11.5 
11.8 
12.5 
12.5 
Distance between the anal tin and the tip of the snout .. 
30.7 
30.3 
35.2 
36.0 
Length of the pectoral fin of the eye side ,, „ ,, ,, ., ,, „ „ 
lO.i 
10.2 
11.6 
11.8 
„ ,. ventral ,. .. .. .. 
8.o 
8.3 
7.7 
7.7 
., „ ,, middle rays of the caudal tin ,. .. ., ,, „ „ „ „ 
18.3 
19.o 
17.o 
16.8 
The internal organs ot the Flounder also corres- 
pond in the most essential respects to those of the 
preceding species. The liver is undivided and oblong, 
and lies on the left side. The spleen is dark red, round 
on one side and flat on the other, and lies by the ven- 
tricle, close to the large, round gall-bladder. The in- 
testine is about 1 V a times as long as the whole fish, 
and lies in coils, without any regular curves, of almost 
uniform diameter, and without any considerable dis- 
tension. It is furnished with two very short pyloric 
appendages. The heart is long and quadrangular. The 
milt-sacs of the male are double and heart-shaped, and 
lie at the extreme end of the abdominal cavity. The 
ovaries of the female are also double as usual, very 
long and pointed; only the broad anterior end lies in 
the abdominal cavity, the long tips being furnished, as 
in the other Flatfishes, with special cavities, one on 
each side of the base of the anal fin. This double 
cavity extends almost to the end of the anal fin. 
The coloration is highly variable. On the eye 
side it is generally gray or yellowish gray, in most 
cases marked with round, pale orange spots, which also 
occur on the fins. The fins are of the same colour as 
the body, but somewhat lighter. The blind side is 
white, but often spotted with brown, especially along 
the lateral line. In specimens where half this side is 
brown, the brown colour always belongs to the caudal 
part. Sometimes, though extremely seldom, the blind 
side is entirely brown. The iris is brassy-yellow, the 
pupil blue. Among the numerous colour-varieties of 
this species there is one, which the Royal Museum has 
received both from the White Sea and the Baltic, with 
the eye side of a uniform blackish blue or plum-colour. 
Siiaw describes a Pleuronectes rosens “ “of the most deli- 
cate rose-colour, slightly tinged in some parts with 
yellowish, and in others with silvery white.” This form 
was taken in the Thames, and was without any spinous 
warts or ctenoid scales. Brown' 1 tells us of a flesh- 
“ Gen. Zoolorj., vol. IV, Pise., p. 302. Cf. Day, 1. c. 
b Edinb. Jonrn. Nat. Geol. II, p. 99, plate II. 
Scandinavian Fishes. 
51 
