1052 
SCANDINAVIAN FISHES. 
wards, has very thick walls, and is bounded from the 
retral duodenum ( duod ) by a strong, annular valve. 
Just behind this valve the upper wall of the intestine 
is pierced with a large hole (app), wide enough for 
the insertion of a finger, and t wo somewhat smaller 
holes, outlets of the large pancreas ( per ), which is 
flesh-coloured with yellowish brown spots, and has been 
formed by the coalescence of the ctecal pyloric append- 
ages", being therefore coursed by numerous, tubular 
passages ( cap ). This gland is of a flattened elliptical 
shape, about 12 cm. long, 8 cm. broad, and 2 1 / 3 cm. 
thick, with sharpened edges. It is situated in the 
circle formed by the above-mentioned gyrations of the 
intestiniform stomach; and in the present case it oc- 
cupies rather more than two-thirds of this circle. The 
duodenum (duod) runs back to a distance of 37 cm. 
depressions on the inside. A similar, though somewhat 
finer network appears on the mucous membrane lining 
the rectum (isp), which is about 50 cm. lorig.'' Here 
we find an apparatus peculiar to the Sturgeon-fishes, 
Ganoids, Lung-fishes, and Selachians. The valve is con- 
tinued by a spiral, in the present case with eight coils, 
which extends almost to the termination of the rectum. 
The spiral consists of a thick raised margin (sp), which 
shows the same depressions as the network of the mu- 
cous membrane, though more sparsely, and which runs 
along the inside of the upper rectal wall, being .con- 
tinuous therewith; but at eight points it detaches itself 
from the roof, and is attached instead by a backward 
membranous spiral (msp) to the rest of the intestinal 
wall. About 2 1 / 2 cm. before the vent the central cord 
of the spiral terminates in a tubercular swelling (tub), 
Fig. 291. Viscera of a male Sturgeon (Acipenser sturio ) 1,845 min. long, taken at Lulea on July 18tli, 1893. About 3 / J0 nat. size. 
Seen obliquely from below. 
abd, right ( abs , left) wall of the abdominal cavity opened and folded back; a pm, inner mouth of the left Mullerian duct (M ) ; app, largest 
of the pancreatic orifices visible in the opened beginning of the duodenum (duod)', cap, section of one of the pancreatic canals; duod, duo- 
denum; h, front part of the liver; hd, right lobe of the liver; isp, spiral intestine, opened; l, spleen; M, left Mullerian duct; msp, spiral 
membrane, the lateral membrane of the spiral valve; per, pancreas, sectioned and with one (the ventral) half somewhat raised to show the 
canals (cap) within it; pijl, pylorus; sp, spira, central cord of the spinal valve; tel, right, ts, left testis, with the posterior half of the latter 
cut loose and laid back behind the left wall of the abdominal cavity; tub, tubercular swelling of the spira ; v, termination of the procurvated 
stomach; ves, dotted line indicating the outlines of the posterior part of the air-bladder, otherwise concealed; i if, gall-bladder; 
* — **, mesorchial thickening of the right testis. 
from the diaphragm, where it abruptly bends forward 
to a point distant about 20 cm. from the same, and turns 
back with equal abruptness, soon passing into the straight 
(spiral) intestine, from which it is divided by an an- 
nular valve. Throughout the course of the duodenum 
the mucous membrane forms a uniform network of 
and the extreme end of the rectum has tive longitu- 
dinal ridges with rather sharp margins on its inside. 
The liver (// — ltd) of the present specimen is of a. bluish 
black colour 0 . The left lobe is about 21 cm long, the 
right lobe (hd) 1 7 1 / 2 cm. The gall-bladder (vf), about 
36 mm. long and 23 mm. broad, lies embedded in 
a Cf. their structure in the Tunny, see above, p. 99. 
b We here adopt Rathke’s division of the intestinal canal. According to others (see, for instance, Wiedersheim, Grundr. Vergl. Anat. 
Wirbelth., p. 412), the greater part of what we here coll the rectum, so far as the spiral valve extends, should be regarded as a part of 
the middle intestine. 
c According to Kroyer it is of a ruddy yellowish brown. 
