Volume 2

The history of British fishes / [Robert Hamilton].

  • Hamilton, Robert, M.D.
Date:
[1876]
Catalogue details

Licence: Public Domain Mark

Credit: The history of British fishes / [Robert Hamilton]. Source: Wellcome Collection.

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    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 preoperculum 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 Salmon 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 • f a circle; the lower margin of the suboperculum is a line directed obliquely upwards and backwards : the line of union of the subopcrculum with the operculum also oblique, and parallel with the lower margin of the suboperculum; the interoperculum narrow vertically, and its union with the operculum