118 HEREDITARY CHARACTERS 



An interesting fact in connection with this cross is that a 

 large proportion of the progeny are deformed. 1 This may 

 be due to the fact that the characters of the two parents are 

 so different that a very slight individual variation in one 

 of the gametes prevents a recapitulation of the blended 

 characters. 



Crosses between the common trout (Salmo fario} and 

 the British char (Salvelinus alpinus) produce sterile off- 

 spring with blended characters. 2 



Crosses between the salmon (Salmo solar) and the sea 

 trout (S. trutta), between the salmon and common trout 

 (S. fario), and between the sea-trout and common trout, 

 all produce fertile offspring with blended characters. 3 



A cross between the salmon (S. salar) and the Loch 

 Lev en trout (8. fario var levenensis) gave very interesting 

 results. The progeny of the first cross were markedly less 

 fertile than either of the parents. Apparently only some 

 of the ova could be fertilised. When, however, the ova 

 produced by the hybrid females were fertilised by pure-bred 

 trout, the progeny were perfectly fertile. 4 



Hybrids between trout, sea-trout, and salmon occur 

 under natural conditions, and the characters are sometimes 

 so intimately blended that it is very difficult or impossible 

 to classify a particular specimen. 5 



Crosses between the roach and bream-flat, the roach and 

 rudd, the chubb and bleak, the common bream and rudd, 

 are not uncommon under natural conditions. 6 Other crosses 



22 St. James's Street, London, S. W. ; Mr. A. W. Armistead, The Solway Fishery, 

 Dumfries ; and the Manager of the Howietoun Fishery, Stirling. All have had 

 personal experience of the cross. 



1 Mr. J. B. Fielding says about 75 per cent. 



2 Howietoun Fishery. 



3 Day, F., British and Irish Salmonidce. 



4 The Manager of the Howietoun Fishery, Stirling, N". B. 



5 I have examined young specimens, with a view to identification, where such 

 important characters as the number of the vertebra were intermediate between 

 two species. 



6 Cuvier and Val., Sackel, Bloch, and Siebold. Quoted by F. Day, British 

 Fishes, London, Williams & Norgate, 1884. 



