GEN. SALMO. THE SALMON. 117 



one-fourth of that amount. The shape is highly- 

 elegant, being oval and moderately elongated, the 

 head small, the greatest depth of the body a little 

 before the dorsal ; the whole form alike indicating 

 great strength and power of rapid motion. The 

 colour of the upper parts is dark bluish-grey or 

 bluish-black, the sides lighter : the abdomen silvery, 

 with a few scattered dusky spots, principally above 

 the lateral line ; the dorsal, caudal, and pectoral 

 fins are dusky black, the ventrals stained with the 

 same on their inner side, the anal white or nearly 

 so. These colours vary considerably, according to 

 age, sex, and season. During and after the time of 

 spawning, the adult male acquires a reddish tinge, 

 and the pre operculum and gill-covers are marked 

 with large reddish blotches. At the same time, 

 particularly in old males, the lower jaw is elongated, 

 and curved upwards in a hook. Besides the distinc- 

 tions derivable from colour, it is desirable to have 

 others of a less variable kind, to prevent the Sahnon 

 being confounded with the other migratory species, 

 to which, in some of their states, they bear a great 

 resemblance. Mr. Yarrell directs attention to the 

 gill-cover, which, in the Salmon, he describes as 

 having the posterior free edge in the form of part 

 of a circle ; the lower margin of the suboperculum 

 is a line directed obliquely upwards and backwards ; 

 the line of union of tlie suboperculum with the 

 operculum also oblique, and parallel with the lower 

 margin of the suboperculum; the interoperculum 

 narrow vertically, and its union with the operculum 



