. British and Irish Salmonidae. Salmon. 54 SALMONID^ OF BRITAIN. Fins.—The rayed dorsal fin in mature fish is a little longer at its base than its highest ray is. Pectoral in adults as long as the head excluding the snout, and does not reach half-way to the yentral, whereas in the par it extends 2/3 of that distance : in the par it is rather pointed, the third to the seventh from the upper ray being the longest. In par and grilse it is about one-sixth longer than in brook trout of the same length. Ventral in adults reaches half-way to the base of the anal, in the par 2/3 : anal one-fourth high
. British and Irish Salmonidae. Salmon. 54 SALMONID^ OF BRITAIN. Fins.—The rayed dorsal fin in mature fish is a little longer at its base than its highest ray is. Pectoral in adults as long as the head excluding the snout, and does not reach half-way to the yentral, whereas in the par it extends 2/3 of that distance : in the par it is rather pointed, the third to the seventh from the upper ray being the longest. In par and grilse it is about one-sixth longer than in brook trout of the same length. Ventral in adults reaches half-way to the base of the anal, in the par 2/3 : anal one-fourth higher than its base is long. The form of the caudal alters with sexual development: in the young par it is deeply cleft, and varies with age in par and grilse (see fig. 17) ; at 2 or 2|- feet in length it is as a rule truncated, and becomes more square* with advancing age. The free portion of the tail is comparatively finer in grilse than it is in adult salmon, and the corners of its tail fin more pointed. Scales—^in the caudal portion of the body they are larger in this than any other British species of the genus, there being from 11 to 12 rows in an oblique line running from behind the adipose dorsal fin downwards and forwards to the lateral- line. Although it has been stated that when the par becomes a smolt a new layer of scales overlaps the old ones, this is erroneous, the silvery pigment which lines the inside of the scales becomes more developed, thus concealing the subjacent It has also been said that the grilse possesses a diamond scale, but this alludes to the appearance of the fish when fresh captured. J The following figures wiU show the form of the scales at various ages. (Fig. 18 a, Fig. 18,a. Scale of par 32 months old, magnified 2 J times. 6. Scale of grilse 46 months old, magnified 3 c. Scale of salmon 16 lb. weight, magni- fied 4J times. b, and c.) The skin on the back of old males, both during and subsequent to the breeding season, being
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Keywords: ., bookcentury1800, bookdecade1880, bookpublisherlondo, bookyear1887
