1884.] HYBRIDS AMONG THE SALMONIDJE. 35 



Dr.GHintker. Non-migratory forms. Salmo hvcnensi< „ 49-90. 



fario,\wt. gaimardi „ 33-46. 



— var. ausonii. . . „ 38-47. 



fa-ox „ 43-49. 



stomachicus „ 44. 



gallivensis „ 44. 



nigripinnis „ 36-42. 



Mr. Day. Non-migratory forms. Salmo fario : — 



Gloucestershire Case, appen . 34-39. 



Cornwall & Cardiganshire ,, 35-44. 



Yorkshire „ 35. 



Sutherlandshire „ 46. 



Salmo levenensis : — 



At Howietoun ,, 47. 



4 <S. salar k 8. levenensis „ -I g„' »g' 



„ Migratory form 2 8. salar, Devonshire... „ 61,71. 



Mr. Arthur. Non-migratory form Salvia fario, var ausonii, „ 43-54. 



New Zealand. 



I do not propose referring to the foregoing, as I have elsewhere 

 (British and Irish Fishes) entered on a consideration of how the 

 Brook-Trout, transported to a warmer climate, and where food is 

 abundant, has taken on a structural change, conclusively showing 

 that the number of cseca is not invariable, but chauges with 

 changing circumstances, and consequently cannot be a criterion of 

 species ; for all the eggs of the Brook-Trout sent to Tasmania were 

 from districts considered by Dr. Giinther to be inhabited by the 

 race ausonii of Salmo fario, in which he had found from 38 to 47 

 csecal appendages only : the same result of change being likewise 

 shown in the transference of Lochleveu Trout to Howietoun. 



I do not propose arguing upon the foregoing premises, but they 

 may tend to prove that in undoubted hybrids the percentage hatched 

 is comparatively small, that the number of malformations is great, 

 and the young appear to be sickly. On the other hand, it does not 

 seem unreasonable to almost doubt whether there exists specific dif- 

 ference between the American and British Charrs, monstrosities 

 being rare, and the young strong. The sole male Charr employed 

 had been some time ready for spawning before beiug used, and 

 doubts were expressed at the condition of the milt. After one or 

 two years' more enquiry, a trustworthy answer may be given ; but so 

 far as hybrids from Howietoun have gone, sterility appears to be 

 the rule, as yet no exceptions having been noticed, but the examples 

 have been few. 



Much stress has been laid upon the number of finger-marks 

 or transverse bars along the sides of various forms of Salmonidse, as 

 characteristic of species. Thus in the second edition of the Parr 

 Controversy (1883) we are told (p. 126) that in the Salmon there are 

 nine or ten", but in the Trout only six or seven ; while those of the 

 Charr are not alluded to. Dr. Giinther, in his ' Introduction to the 

 Study of Fish,' repeats the popular idea when he observes, " The 

 number of bars is not quite constant, but the migratory Trout have 

 2 (and even 3) more than the River-Trout" (p. 631). 



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