628 



SCANDINAVIAN FISHES. 



itit'crinr inargin lies in the line lietwecn tlie iiiuutli and ; which opens into the stoniMch (r). The hitter, wliich is 



the upper corner of the gill-opening, and the distance i scarcely divided externally from the short (esophagus, 



between them and the tip of the snont is somewhat extends along the greater part of the dorsal wall of the 



greater tiiaii tiiat between them and tlie gill-o])euings. alidominal cavity, and under the end of this wall passes, 



Externally they are rather small, somewhat oblong (el- ; without external boundary but with an internal con- 



liptical) ill form, witii a longitudinal diameter of about i traction, into the intestine, which first runs straight for- 



11) or 17 % of the length of the head or ^3 of the I ward and then, with several bends within its sjiecial 



breadth of the interorltital space. The eyeballs them- peritoneal (mesenteric) sac (fig. 156, 0, coils Ijackwards 



selves, however, are remarkable for their great size; in 

 Hastixg's specimen, which was nearly l^/^ m. long, the 

 transverse diameter of the eyes was 6V2 cm. A most 

 remarkable point in the eyes of the Sunfish is the inner 

 eyelid, the mol)ile, nictitating membrane, pierced in the 



and forwards, until it passes straight down into the 

 rectum (/) and pierces the thick wall of the abdominal 

 cavity at the vent (fig. 1.56, a). The entire intestinal 

 canal is about S^;^ — .5 times as long as the body, and 

 is especially remarkable for its thick wall. The spleen 



middle, with whicii this fish is fui-nished according to 1 is of a flat, rounded shape, dark reddish blue in colour. 



('uviER and Owkx". A similar nictitating raemlirane 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. Ikit iiere tiiis niend)rane is furnished with a 

 special closing muscle (sphincter) and five radiating 

 opening muscles, the latter of whicli oi-iginate from 

 the bottom of the orbit. The nostrils are very small, 

 the anterior in each pair elliptical and transversely-set, 

 the posterior i-ound. 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 ^/^ — ^/\ of the length of the latter. 



The tongue, according to Khoyer, is very large and 

 fleshy, rather like the human tongue, but with very short 

 and flat papilla'. Both the tongue and the palate are 

 sharp as a rasp, almost as sharp as the skin of the liody. 

 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 onlj' slightly de\eloped and not dentated. 

 The fourth branchial arch coalesces with the clavicular 

 arcli''. The ui^per jjharyngeals form on each side an 

 almond-shaped disk, set with three transverse rows of 

 5 — 8 pointed, scattered and narrow, Ijut fairly large, 

 curved teeth; the lower pharyngeals are toothless. 



The abdominal cavity is lined with a firm, hard, and 

 white peritoneum (fig. 156, jn). 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 onlj' a small lobe to the right. The gall- 

 bladder (fig. 157, rf) is large and has a long duct, 



and lies between the liver and the stomach. The urin- 

 ary bladder (fig. 157, ri() is large and of an elongated 



vj i r 



Fig. 157. Intestinal uniinl of Orthagoriscns mold, on a reduced scale. 



After Cleland. 



c, tlie stomiicli; «, tlic ureter; an, the fissure-like mouth of the 



urethra in the wall of the urinary bladder; vu, the urinary bladder: 



or, the ovary; r. the rectum; ;', the intestine; c/, the gall-bladder. 



pear-shape. Its ujjper wall is pierced by the ureters 

 (ti), subsequent to their union. In front of this bladder 

 lies the simple' o\nry (or), with the oviduct following 

 the front side of the urethra down to the common uro- 

 genital a]5erture behind the vent. The rudimentary air- 

 bladder, which was discovered by Costa, occupiies 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. 



" CnviER, Leqons d'Auat. Comp. (ed. Dumekil) tome 11, ji. 434; (ed. Meckbi.) tome II, p. 437; Owen, Comp., Anat., Phi/sioL, vol. I, p. 336. 



' According to Kr0YER. According to Cleland it is free. 



' According to Clelanp and Wahlgren. According to Costa there are two distinct ovaries. 



