30 FISH AND FISHING IN SCOTLAND. 



intestines. The head of fishes, in consequence of the form and 

 position of the gills and their gill covers, include those organs 

 which indicate the strength of the digestive organs, and of the 

 respiratory ; that is, the jaws and the gills. Thus the size of the 

 head, cceteris paribus, affords valuable natural history indications 

 in respect of the habits of the species. If, in addition to these, 

 we add the locomotive organs found in fishes, i. e. the fins and 

 tail, we have three valuable indications of habits and points of 

 comparison with others ; specific characters, in fact, which time 

 nor place can alter during the existing order of things, unless the 

 extreme theories of the good Lamarck be admitted as true. 



If ^ve now examine the trout of the estuary with reference, 

 not so much to those spots and external colouring (though these 

 also in a natural history sense are valuable and important), but 

 to those grand features more immediately connected with the 

 vital functions, comparing them with other species of the trout 

 kind, we shall find, that the head (gills included) and fins are 

 smaller than those of the common red-spotted trout of rivers or 

 of the fresh waters, implying that the fish is less voracious, less 

 active ; that in its flesh it is pink-coloured and most excellent in 

 flavour, dependent no doubt, in part, on the gammari shrimp or 

 small shrimp on which it lives, but mainly, no doubt, on the 

 nature of the fish itself ; that the gape of the mouth is smaller 

 than that of the common river trout, but larger than that of the 

 Loch Leven, a fish of still more tranquil habits. Trout resembling 

 these have been taken, as I have been assured, in the Forth, and 

 in the Esk, in Eskdale, Yorkshire. 



In August, in some of these trout, the milt was largely 

 developed. Its teeth are nearly as large again as in the Leveii 

 trout. The pancreatic cceca are thirty-six, and the longest of 

 these measured one inch. The dentition was as follows : 



Maxillary 25 50 



Intermaxillary 10 = 20 

 Palatine 14 28 



Yomerine 10 20 



in a double alternating row, and placed, of course, mesially : 

 Lingual 6 12 



