872 PROFESSOR W. C. M‘INTOSH AND MR E. E. PRINCE ON 
The net is small enough to capture larval cod, but they are not a conspicuous feature, 
very few having been seen, and the intermediate stages between the larval form and the 
post-larval are difficult to obtain. The latter apparently tend shorewards in the end of 
April, not at the surface, but in the deeper parts of the water, many, indeed, being by 
and by caught on the bottom by a fine trawl-net. They sport about amongst the tangle- 
forests and shallow water and neighbourhood, and as they get older seek the deeper 
parts near the rocks.* They then, as Sars says, form shoals in deep water on the various 
fishing banks, large numbers being caught the following summer both by liners and 
trawlers. 
That a migration occurs in other Gadide is apparent when we consider the case of 
the ling. Asa rule, the old ling frequents the deeper parts, yet the young, ranging from 
5 inches upward, are plentiful off the Pier Rocks at St Andrews, especially in their barred 
or tesselated condition. The post-larval haddock also would appear to frequent the 
deeper water, as also does the post-larval whiting, the latter occurring in considerable 
numbers south-east of the Island of May, and at a later period than the post-larval cod. 
When older, viz., from 3 to 6 inches, they are not uncommon in St Andrews Bay at low 
water. The larval frog-fishes and other types follow the same habits. 
On the other hand, some of the ordinary Pleuronectidee, e.g., the flounder, take a 
somewhat different course. The larval forms are pelagic on the sites t frequented by the 
adults, and then they gradually seek the bottom as well as the tidal margin, especially 
the mouths of streams, in May, June, July, and August. They may be found in lessened 
numbers there till well grown, so that the migration of this form is slight. The young 
plaice appears to follow similar habits, but the large adults seek the deeper water off 
shore. The same may be said of the turbot, the brill, and the long rough dab. The 
larval forms of the craig-fluke (Plewronectes cynoglossus) frequent the ground occupied 
by the adults, and various stages may be secured by the same haul of the net. On the 
whole, then, the evidences of migration relate only to the passage in certain species of the 
post-larval stage to the shallower water, and the tendency of all the healthy larger forms 
to seek the deeper water. ‘The latter feature, for instance, is observed in the halibut. 
It is apparent, however, that certain flat fishes, e.g., the “ witch” or craig-fluke, so far as 
at present ascertained, are confined for the most part to the deeper water and soft ground, 
both in their adult and their younger stages ; and Miiller’s topknot, the lemon dab (to some 
extent), and others probably agree with them in this respect. It appears to be a feature 
of moment that the post-larval forms of such as the “ witch” and long rough dab swim 
somewhat longer on edge—that is, are larger fishes with great depth of body before the 
eye travels round, and before settling on the bottom. The post-larval stages of the 
flounders and plaice appear generally in April, and are about half an inch or less in length, 
their eyes as a rule being lateral in position; and as the season advances the left eye 
moves forward a little, and approaches the dorsal edge. They vary considerably in size 
at a given time, but not so much as the “witches” formerly alluded to, and would 
* Vide No. 104, p. 309. + Generally inshore. 
