5°° 
TUB E-B LADDERED GROUP. 
river-trout may be taken the Lochleven trout, which is somewhat silvery during 
the smolt-stage, with the spots generally black, and no orange border to the fatty 
fin, but at a later stage assumes the general coloration of the river-trout, although 
lacking the white black-based front margin to the dorsal, anal, and pelvic fins 
characteristic of the latter. Silvery trout do, however, occasionally occur in fresh 
waters, where there is no possibility of their having migrated from the sea. In 
concluding his observations concerning the coloration of trout, Day writes that 
“ reasons have been shown for admitting that sea-trout might breed in fresh waters 
without descending to the sea. That they can be traced step by step, and link by 
link, into the brook-trout, and vice-versa ; that the Lochleven trout, which normally 
possesses a smolt- or grilse - stage, passes into the brook-trout; and also that 
breeding any of these tw r o forms together sets up no unusual phenomena,” Later 
on, he observes that some of the chief distinctions between the sea- and fresh-w T ater 
forms of trout consist in the comparatively more complete system of dentition in 
the fresh-water races, their generally longer head, blunter muzzle, and stronger 
upper-jaw, irrespective of the smaller number of blind appendages to the intestine. 
The dentition is, however, excessively variable; and specimens with the coloration 
and form of the river-trout taken in estuaries, or even in the sea, usually have the 
small number of vomerine teeth characteristic of the migratory forms; while, on 
the other hand, fresh-water examples with the coloration of the migratory type, 
may have a dentition of the nonmigratory type. “ It has been asserted that 
brook-trout invariably have a double row of teeth along the body of the vomer, 
and some authors have gone so far as to assert that these teeth are not deciduous. 
Doubtless it is not uncommon to find trout up to 2 lbs. weight, or even more, with 
all the vomerine teeth thus remaining intact when a double row is present; but 
it is by no means rare to see only one irregularly-placed row, while in very large 
specimens these teeth (unless they have entirely disappeared) are always in a 
single row, and the vomer may be found toothless, or with only one or two teeth 
at the hinder edge of the head. Equally incorrect is the statement that the teeth 
disappear differently in different forms, for in all they first assume a single row, 
and then fall out, first commencing from behind. But in the rapidly growing 
sea-trout the vomerine teeth are shed sooner than in the brook-trout.” The limits 
of our space preclude our entering further into the consideration of this interesting- 
subject. The ordinary sea-trout, which is essentially a North-European fish, much 
more common in Scotland than in England, and grows to a length of 3 feet, is 
depicted in the lower figure of the illustration on p. 493; while, as an example of 
a spotted form, we take a variety of the Continental lake-trout (S. lacustris), 
shown in the upper figure of the illustration on p. 499. Known on the Continent 
as the maiforelle (May-trout), this fish has the sides of the body marked with 
irregular angular or X-shaped black spots, between wdiich are red spots, these 
spots becoming less numerous beneath the lateral line, wdiile the under surface 
may be tinged with red. On the gill-cover the spots are larger and more rounded. 
In the typical variety of this trout, from the Lake of Constance, the spots do not 
extend below the lateral line; this form being known as the schwebforelle. The 
migrations of the sea-trout are very similar to those of the salmon; in Sutherland 
the gieat run of these fish to the sea taking place in June, while they reascend 
