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 colouring.f 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 times. 



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 thickened and spongy, causes the scales to be more or less 

 imbedded. 



Colours. — In adults superiorly of a steel blue, becoming lighter on the sides 

 and beneath. Mostly a few rounded or x-shaped spots scattered over the body 

 above the lateral-line and upper half of the head, § being more numerous in the 



and apparently the same age, having no teeth on the tongue, this organ being perfectly smooth. 

 I have examined many this season, and I find almost as many smooth-tongued ones as those 

 having teeth. This is not a sexual peculiarity, as I find them about equal. The first I examined 

 weighed on an average from 8 lb. to 14 lb. or 16 lb. each." Frank Gosdeu, Land and Water, 

 November 28th, 1885, wrote on this subject : " I have restricted my examinations to salmon from 

 the Exe and the Dart in Devonshire." ..." Mr. Couch, I am aware, as well as many others, has 

 taken notice of the teeth on the tongues of salmon : but I do not know of anyone having remarked 

 upon salmon of the same age or about, some having teeth others no teeth upon the tongue. For 

 several consecutive seasons I have examined numbers of salmon varying from 6 lb. to 30 lb. each 

 and have found it immaterial whether they be large or small." 



* The existence of valves in the large intestines has already been alluded to (page 22 and 

 fig. 12). The gut was removed from the fish, hardened in a solution of chromic acid, and injected 

 the next day with plaster of Paris. 



t This will be more fully considered under the head of the " life history of the smolt." 



t Mr. Anderson (September 80th, 1885) wrote: "I think you mistake me when I say the 

 grilse has a diamond scale. It is only this appearance upon the fish when you see it newly 

 caught, but loses it in a few hours ; it, as well as the salmon scale, takes on a different 

 appearance after six hours." 



§ March 26th, 1884, 1 was shown three salmon, all males, and about 12 lb. weight each, and all 

 caught in the Severn the same day by one gang of fishermen. One had no spots on the head, 

 one ten, and the third twenty, showing how disgimilarly these fishes may be marked at the same 



