840 
SCANDINAVIAN FISHES. 
The spinal column is also marked by its weak 
ossification. The neural arches proper (Owen’s neurapo- 
pliyses) are persistently cartilaginous in most of the 
abdominal vertebrae, and the bases of their neural 
spines are united to the bodies of the vertebrae only by 
a suture or, in young specimens and in the anterior 
part of the column, by a mobile articulation. In the 
forepart of the skeleton these spines are also but loosely 
united to each other, the right to the left in each ver- 
tebra, and with the hind surface of each base articulates 
a rib-like muscular bone, directed outwards, backwards, 
and upwards (Owen’s diapophysis). In the posterior 
part of the abdominal region the cartilaginous neural 
arches disappear, the bases of the neural spines take 
their place and develop a firmer osseous connexion with 
the bodies of the vertebras, the neural arches thus 
formed being strengthened at the same time by the 
coalescence of the spines on each vertebra. The diapo- 
physes decrease in length, and disappear near the caudal 
region; but simultaneously there appear, though with 
only slight development, the knob-shaped articular pro- 
cesses {zyg apophyses) that in the Cyprinoids are gene- 
rally so prominent on the anterior abdominal vertebrae, 
one pair in front of and one pair behind the neural 
arches, which are here most constant in the caudal 
region, though even there they may be wanting. The 
development of the haemal arches proper (Owen’s hcem- 
apophyses) takes the reverse direction. It advances from 
the front of the body to the posterior part thereof: on 
the first vertebra they are scarcely distinguishable ex- 
ternally from the body of the vertebra; on the second 
vertebra they are distinct protuberances, one on each 
side of the lower part; on the third each of them is 
furnished with a rib; and they thus continue to in- 
crease until, near the caudal region, a succession of 
haemal spines appears, each bearing a pair of ribs on 
the hind surface of its top, while the haemal spines of 
each vertebra approach each other at the top, forming 
(usually on the last six abdominal, as well as on the 
caudal vertebrae) a closed haemal arch. On the same 
vertebrae as the haemal spines, there also appear lower 
articular processes similar to the upper. The ribs are 
slender, in sharp contrast to those of the Cyprinoids. 
In the shoulder-girdle, the structure of which is 
else the same as in the preceding family, the clavicle 
is thin and broad, with the upper arm comparatively 
short, and the postclavicle consists of three, sometimes 
four parts, namely two (sometimes three) upper, thin 
and flat, and one lower, pointed and rib-like. This 
division of the postclavicle recurs in the Herrings. 
The pelvic bones are simple and triangular, with- 
out the indentation in front, and with only a rudiment 
of the process behind, which we have seen in the Cy- 
prinoids. But remnants of the older piscine types’ 
radialia (mobile basal bones of the ventral rays) and also 
of the true pelvis of the said types, have been detected 
in the Forell stage by Davidoff". 
The intestinal canal is rather simple and short, as 
in most predatory fishes, its entire length, when ex- 
tended, being about equal to the length of the body or 
somewhat less than the latter. The stomach is only 
faintly marked off from the rest of the canal; but a 
remarkable point is the thickening of its walls which 
attends a diet of mollusks or other testaceans * 6 . This 
thickening lias been most frequently observed in the 
so-called Gillaroo Trout of Ireland, a form which has 
hence been named by Gunther Salmo stomachicus ; but 
it may also be observed in common Lake Trout 0 . The 
pyloric part is directed forwards, as well as the be- 
ginning of the true intestine (duodenum), which is ex- 
ceedingly well furnished with csecal diverticula. These 
appendages, however, vary considerably both in size 
and number, from about 30 to nearly 100. They are 
generally most numerous in the Salmon proper, where 
Krdyer 6 * has counted 96, though the usual number in 
this form is between 50 and 70. In the Trout that 
migrate to salt water, the usual number is about the 
same; but in those that live exclusively in fresh water, 
it is generally less, about 30 — 50. Thus in different 
specimens of Trout 29 — 69 pyloric appendages have 
been counted 0 . After the duodenum has advanced al- 
most to the diaphragm, the intestine abruptly bends 
a Morph. Jahrb., XVI (1880), p. 464, taf. XXI, fig. 5. 
6 According to Day a seagull at Hunter’s Museum was fed for some time on corn, and the muscular layers of its stomach were 
thereby thickened as in a crop; and from Holmgren’s experiments on pigeons at Upsala it appeared that the muscular layers in their crop 
were reduced by a flesh diet. 
c It is further known that a molluscous diet gives the body of the Salmons a singular, orange ground-colour. 
d Damn. Fislce, Bd. 2, p. 558. 
e Day, British Salmonidce , p. 188. 
