628 
SCANDINAVIAN FISHES. 
inferior margin lies in the line between the mouth and 
the upper corner of the gill-opening, and the distance 
between them and the tip of the snout is somewhat 
greater than that between them and the gill-openings. 
Externally they are rather small, somewhat oblong (el- 
liptical) in form, with a longitudinal diameter of about 
16 or 17 % of the length of the head or 1 / 3 of the 
breadth of the interorbital space. The eyeballs them- 
selves, however, are remarkable for their great size; in 
Hastings specimen, which was nearly 1 1 / s m. long, the 
transverse diameter of the eyes was 6V 2 cm. A most 
remarkable point in the eyes of the Sunfish is the inner 
eyelid, the mobile, nictitating membrane, pierced in the 
middle, with which this fish is furnished according to 
Cuvier and Owen". A similar nictitating membrane is 
common, it is true, among’ the Sharks and finds its ana- 
logue, to a certain extent, in the motionless, adipose 
membrane of the Mackerels, the Gray Mullets, and other 
Teleosts. But here this membrane is furnished with a 
special closing muscle (sphincter) and five radiating 
opening muscles, the latter of which originate from 
the bottom of the orbit. The nostrils are very small, 
the anterior in each pair elliptical and transversely-set, 
the posterior round. They are set on about a. level 
with the centre of the eyes and rather near each other, 
the anterior one at a distance from the tip of the snout 
that measures about % — 3 / 4 of the length of the latter. 
The tongue, according to Kroyer, is very large and 
fleshy, rather like the human tongue, but with very short 
and flat papillae. Both the tongue and the palate are 
sharp as a rasp, almost as sharp as the skin of the body. 
In front of the tongue we find in the lower jaw (but 
not in the upper) a large, transverse fold (velum). The 
gill-rakers are only slightly developed arid not dentated. 
The fourth branchial arch coalesces with the clavicular 
arch * 6 . The upper pharyngeals form on each side an 
almond-shaped disk, set with three transverse rows of 
5 — 8 pointed, scattered and narrow, but fairly large, 
curved teeth; the lower pharyngeals are toothless. 
The abdominal cavity is lined with a firm, hard, and 
white peritoneum (fig. 156, p). The liver ( h ), which is 
of a rounded, oval shape, occupies about half, or even 
nearly the whole, of the abdominal cavity on the left 
side, but has only a small lobe to the right. The gall- 
bladder (fig. 157, vf) is large and has a long duct, 
which opens into the stomach (v). The latter, which is 
scarcely divided externally from the short oesophagus, 
extends along the greater part of the dorsal wall of the 
abdominal cavity, and under the end of this wall passes, 
without external boundary but with an internal con- 
traction, into the intestine, which first runs straight for- 
ward and then, with several bends within its special 
peritoneal (mesenteric) sac (fig. 156, i), coils backwards 
and forwards, until it passes straight down into the 
rectum (r) and pierces the thick wall of the abdominal 
cavity at the vent (fig. 156, a). The entire intestinal 
canal is about 37 2 - — 5 times as long as the body, and 
is especially remarkable for its thick wall. The spleen 
is of a flat, rounded shape, dark reddish blue in colour, 
and lies between the liver and the stomach. The urin- 
ary bladder (fig. 157, vu) is large and of an elongated 
v u au vu 
Fig. 157. Intestinal canal of Ortliagoriscus viola, on a reduced scale. 
After Cleland. 
v, the stomach; u, the ureter; an, the fissure-like mouth of the 
urethra in the wall of the urinary bladder; vu, the urinary bladder; 
ov, the ovary; r. the rectum; i, the intestine; vf, the gall-bladder. 
pear-shape. Its upper wall is pierced by the ureters 
(it), subsequent to their union. In front of this bladder 
lies the simple c ovary (ov), with the oviduct following 
the front side of the urethra down to the common uro- 
genital aperture behind the vent. The rudimentary air- 
bladder, which was discovered by Costa, occupies an 
oblique position, high up at about the middle of the 
length of the abdominal cavity. 
In the leading features of its coloration the Sunfish 
shows itself to be a strictly pelagic fish, von Wright’s 
figure tells us better than words the appearance of a 
Sunfish about half a metre long; but if we compare 
this figure with Costa’s figure of a somewhat older fish, 
we find that quite a considerable variation may occur 
in the colour. The ground-colour is bluish gray, 
“ Cuvier, Leqons d’Anat. Comp. (ed. Dumeril) tome II, p. 434; (ed. Meckel) tome II, p. 437; Owen, Comp., Anat., Physiol., vol. I, p. 336. 
6 According to Kr0Yer. According to Cleland it is free. 
c According to Cleland and Wahlgren. According to Costa there are two distinct ovaries. 
