2876 THE BONY FISHES AND GANOIDS 



admitting that sea trout might breed in fresh waters without decending to the sea. 

 That they can be traced step by step, and link by link, into the brook trout, and vice- 

 versd; that the Lochleven trout, which normally possesses a smolt or grilse stage, 

 passes into the brook trout; and also that breeding any of these two forms together 

 sets up no unusual phenomena." Later on, he observes that some of the chief dis- 

 tinctions between the sea- and fresh-water forms of trout consist in the compar- 

 atively 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 two pounds 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 three feet, is depicted in the lower figure of the illustration 

 on p. 2869; while, as an example of a spotted form, we take a variety of the Con- 

 tinental lake trout (S. lacustris}, shown in the upper figure of the illustration on 

 p. 2875. Known on the Continent as the maifordle (May trout) this fish has the 

 sides of the body marked with irregular angular or X-shaped black spots, between 

 which are red spots, these spots becoming less numerous beneath the lateral line, 

 while 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 great run of these fish to the sea taking place in June, 

 while they reascend the rivers in autumn to spawn. Jardine writes that "in 

 approaching the entrance of rivers, or in seeking out, as it were, some one they pre- 

 ferred, shoals of this fish may be seen coasting the bays and headlands, leaping and 

 sporting in great numbers, from one to three or four pounds in weight; and in 

 some of the smaller bays the shoals can be traced several times circling it, and 

 apparently feeding." On the other hand, the Continental May trout spends the 

 colder months in the deepest waters of the mountain lakes, only coming to the sur- 



