230 Field and Forest Rambles. 



the upper surface of the head. The inter-operculum (i) is 

 short and triangular, the sub-operculum (/>) is about half as 

 high as the operculum (o). The pre-operculum (s) has its 

 lower margin well rounded, resembling a shepherd's crook, 

 with the extremity turning tipwards, and not forwards, as in 

 many allied trouts. 



The triangularly-shaped cluster of sharp teeth on the outer 

 part of the vomer is another pointed character. The lingual 

 teeth appear to vary in number from three to six on each side, 

 but I am not certain if this is not a sexual distinction, or con- 

 nected with age ; the gill rays also vary from eleven to twelve 

 on either side. The fin formula is as follows : — Dorsal rays, 

 10-13 ; pectoral, 12-13 ; ventral, 8-9; anal, 10; caudal, 1 9§ -f . 



BROOK TROUT. 



The lateral line contains 116 scales; the vertebrae are 68; 

 and there are 38-39 pyloric cceca. The above are the 

 only safe characters whereby this trout is to be distin- 

 guished ; indeed the naturalist or fisherman trusting to out- 

 ward aspect and colouring must be prepared to meet per- 

 plexity in every brook and inland water. The lower fins 

 have invariably white margins, with more or less of a black 

 lining, whilst the vermilion and golden spots, red hues, and 

 pale of the belly are subject to much diversity, and are 

 unquestionably connected with the food and haunts of the 

 individuals. Thus, the darker shadings will invariably be 

 found in the denizens of muddy lakes and dark waters, 



