Akthuk. — Notes on some Sjiecimens of migratory Salmonidea. 175 



After retaining this length for some distance they gradually get shorter, 

 till near the top of the nose they have dwindled to a length of 1^ inches. 

 On the inner side of this principal set of baleen, and close to the palate, a 

 smaller fringe is observable, of which the baleen, where longest, reaches the 

 length of 1^ inch, by a breadth of 1 inch. 



This inner fringe is separated by a well-defined line of division fi-om the 

 larger baleen, and shows, at the same time, three or more lines of division, 

 so that the base has quite a reticulated appearance. 



That the larger and smaller series are quite distinct from each other is 

 well exhibited on the base, because, although in some parts the line of the 

 large baleen is continued into the inner fringe, in others this is not the case, 

 the inner baleen beginning on the line of division between the baleen plates 

 of the larger series. 



Art. XIX. — Notes on some Specimens of migratory Salmonidre. 



By W. Arthur, C.E. 



[Read before the Otago Institute, 2it]i August, 1880.] 



Plates IV. and V. 



Before referring specially to the individual specimens I have been able to 

 secure, I may perhaps be permitted to remind you that the study of the 

 Salmonidffi is that of the most difficult and perplexing branch of ichthyology. 

 This is due to the following circumstances :— the close relation between 

 some of the species ; the numerous varieties of the same species ; the con- 

 fusion arising fi-om the same fish being differently named in different locali- 

 ties, or erroneously named ; and lastly, the want of completeness and pre- 

 cision of description in the writings of many who have undertaken to de- 

 scribe fish. 



General remarks on well known species. 



To illustrate in a general way the many varieties which occiu: of the 

 same species, I would direct your attention to the species S. salar, S. trutta, 

 and S. fario, of the British genus Sahno. 



I have seen individuals of the species S. salar — the true salmon — from 

 the Tay, the Tweed, Solway, Clyde and tributaries, Awe, Orchy, Lochy, 

 Ness, Dee (Aberdeenshire) ; from several English rivers, as the Tyne, 

 Dee, etc., and from the west of Ireland. These were all specifically 

 the same fish, yet possessing individual characteristics sufficient to uidicate 

 and distinguish the fish of one river from those of any of the others. For 



