82 PHYSOSTOMI. 



by pollutions, or obstructions render its ascent impracticable. In Great Britain 

 most numerous towards Scotland : it abounds in all Yorkshire rivers, unless 

 excluded by pollutions (Yorkshire Vertebrata), less common down the east coast 

 of Lincolnshire, Norfolk, and round the south coast, the English Channel, but 

 more frequent in the Bristol Channel, while the Severn salmon are among those 

 which are most esteemed. 



A salmon weighing 25 lb. was captured off Lowestoft in a trawl net (Colman, 

 Land and Water, May 10th, 1879), being only the second instance since 1849. 



Sir T. Browne, 1662, stated that it was no common fish in the rivers in his 

 time, though many were taken in the Ouse, in the Bure, and in the Waveney, in 

 the Norwich river but seldom, and in the winter. Paget observes, respecting 

 Yarmouth, that small ones have very rarely been captured in the mackerel nets. Of 

 late years they have almost disappeared from the Norfolk coast, and one taken 

 December 1st, 1873, in a flooded meadow at Lakenham, was considered such a 

 curiosity that it was sent to London for identification and preservation ; it is 

 now in the Norwich Museum (Lowe). Yarrell remarks that the last Thames 

 salmon was captured in June, 1833. 



The size to which this fish attains depends upon the extent and character of 

 the water it inhabits, the quantity and quality of its food, temperature, and other 

 circumstances. It has been surmised that the very small salmon sometimes 

 captured are really grilse, which having failed to ascend have to defer such to 

 the succeeding year, when they have become salmon. The reason why some 

 Dutch fish are so large is believed to be owing to so many kelts escaping capture. 



Pennant mentions one of 74 lb. Buckland cast one of 70 lb., 4 feet 5 inches 

 long, taken from the Tay. In 1867 one was taken in the Severn, near Lydney, 

 in July, weighing over 42 lb. ; another the next month at Beachley, nearly 

 52 lb. ; and a third in the Wye, near Tintern, over 40 lb. In 1873 one weighing 

 70 lb. was taken in June at Littleton. In Ireland, Ball recorded two, each 

 weighing 52 lb., captured at the same time at Blackwater : several instances of 

 70 lb. fish are alluded to by Thompson, and in July, 1881, an Irish fish upwards 

 of 84| lb. weight was exhibited at a fishmonger's in Manchester. 



The figure of the salmon, plate ex, fig. 1, is of a male 32 inches long, taken 

 from the Severn. The parr, fig. 2, is slightly reduced from one captured in the 

 Teme in the month of May. The figure of the kipper, plate cxi, fig. 1, is from 

 Dr. Gunther's type specimen of Salmo argenteus (not Cuv. and Val.), a female 

 26 inches long, which had been kept for a short time in a fresh water pond. 



b. Fourteen or more rows of scales between the soft dorsal fin and the lateral-line. 



Prior to giving descriptions of the various forms of Salmones, included by 

 some authors under this head, it appears most appropriate to explain why it is 

 that I find myself unable to accept these numerous species, believing those 

 ichthyologists more correct who have considered them modifications of only one, 

 which, as Salmo trutta, includes both the anadromous and non-migratory fresh 

 water forms. In following out this inquiry, it will be perhaps best to show 

 (1) that marine salmonoids may take on a fresh water existence ; (2) that Salmo 

 trutta and 8. cambricus can be both traced into the fresh water forms of the 

 common brook trout (see page 59), while crossing the ova of one with the milt 

 of the other gives rise to no remarkable symptoms, and the progeny, if hybrids, are 

 not sterile. Sir J. Gibson-Maitland, in the winter of 1881, crossed the ova of the 

 Loch Leven trout with the milt of the sea-trout, and about 95 per cent, hatched. 



In order, however, to facilitate reference and draw attention to some phenomena 

 still requiring elucidation, I have placed as distinct Salmo trutta, with its very 

 deciduous vomerine teeth, and 8. fario, or the brook-trout, with them more 

 persistent, in short by the parr dentition being continued through life, and a 

 somewhat different geograpbical distribution. Also 8. levenensis which appears 

 to be in a transition state from an anadromous marine to a non-migratory fresh 

 water lake variety. 



If sea-trout which having entered fresh water in order to breed, are prevented 

 returning to the ocean, it may result, as detailed by a correspondent in the Field 



