852 
SCANDINAVIAN FISHES. 
the height of the anal tin. But in the young this cha- 
racter loses its validity, as well as in very old male 
Salmon during the spawning-season. The length of 
the maxillaries is, as a rule, less in the Salmon, greater 
in the Trout, than 8 % of that of the body or 36 % 
of that of the head; but the character, which was ori- 
ginally sexual, applies only to typical specimens. Sal- 
mon, as mentioned above, in general have comparatively 
larger scales than Trout. Gunther and Day have ex- 
pressed this by the statement that, in an oblique trans- 
verse row forward from the posterior extremity of the 
A B 
Fig. 212. Vomer of a Salmon (H) and a Trout ( B ), seen from 
below (a) and from the left ( b ). Natural size. After v. Siebold. 
adipose tin to the lateral line, the Salmon has If or 
12 scales, the Trout 13 — 15. But even this character 
holds good only in typical specimens 0 , and sometimes 
the two sides of the body differ in this respect*. 
Among the internal characters that may be used 
to distinguish Trout from Salmon, we have above 
mentioned the number of the gill-rakers, which in the 
outer row on the front of the first branchial arch is, 
as a rule, under 17 in the Trout, over 17 in the Sal- 
mon, or, if it lie greater in the former, made up in 
front and at the anterior upper corner of verrueose, 
spiniferous protuberances. Another character, derived 
from the shape and dentition of the vomer, has received 
special attention of v. Siebold. In typical Salmon the 
head of the vomer has a more or less distinct pent- 
agonal or hexagonal shape, in Trout it is triangular. 
In the former the vomerine teeth disappear earlier, and 
in old Salmon are sometimes almost entirely wanting; 
whereas even the oldest Trout commonly have several 
teeth not only in a transverse row on the base of the 
head of the vomer, but also in a double or single row 
along the carina on its shaft. 
But these internal characters are no more trust- 
worthy than the external: the naturalist who examines 
hundreds of specimens will find them too often merged 
in each other. 
Note. One of the best examples to show the relation of the 
two varieties to each other, as regards the last-mentioned characters, 
seems to be afforded by the attempts to introduce the typical Salmon 
into the Lake of Geneva 0 . These experiments were commenced by 
the hatching of Salmon eggs from the Rhine and from the hatchery 
of Hiiningen; but the fry excluded from these ova escaped into 
the Rhone, and none of them was ever regained and identified with 
certainty. From 1857 to 1860, according to Chavannes, about 7,000 
fry were placed in the feeders of the lake, and during 1863 about 
4,600; and in 1882 a pisciculturist, Lugrin by name, is said to 
have deposited nearly 100,000 Salmon fry in the Rhone near Geneva. 
Hardly any results, according to both Lunel and Fatio, are known 
to have been attained by these experiments: the ‘Salmon’ which have 
been caught from time to time in the Lake of Geneva, have proved 
on closer examination to be Trout. The latter author, however, is 
still dubious with regard to at least three finds. In these specimens 
Trout and Salmon characters were blended, and especially in two of 
them the vomer was most nearly approximated to its Salmon type. 
Though it is indeed possible that all the Salmon fry have been de- 
stroyed, it seems more probable that during growth the fry have 
passed to the Trout form, as this appears in its normal development 
where the water offers to the fish no practicable means of commu- 
nication with the sea. 
The Salmon is so well known that a minute de- 
scription would be here superfluous, especially as it 
differs but slightly from the Charr, which we have 
just described. We may instead refer the reader to 
our figures and to the following comparative table of 
the most important external characters, expressed in 
averages which have been computed 1) in the first 
two columns, from our measurements of Trout in the 
For ell, Oring, and Salmon stages and of typical Sal- 
mon at the same periods of growth, 2) in the third 
column from all these measurements combined for each 
character, and 3) in the fourth column from the cor- 
responding measurements of Scandinavian Charr. 
° To Salmo trutta fluviatilis (the Freshwater Trout) Day assigns in his last work (Brit., Ir. Salmonidce, p. 199) 12 — 15 scales 
in the said row. 
6 See, for example, specimens Nos. 284, 285 and 306 in Tabula metriea IV in Smitt's Riksmuseets Salmonider. 
c See Lunel, 1. c., pp. 128 — 130, and Fatio, 1. c., pp. 308 — 313. 
