84 PHYSOSTOMI. 



received in the British. Museum in 1874 ; it externally shows the normal form of 

 the common sea-trout (plate cxi, fig. 2), but has only 36 ccecal appendages, so 

 that (if Dr. Giinther's theory were correct) it ought to be a sewin, 8. cambricus. 

 This difficulty is surmounted by suggesting that this fish is a hybrid, but as 

 the sewin and the sea-trout are asserted by Dr. Giinther to reside in different 

 districts, and as only anadromous sea trout were deprived of eggs and milt, 

 by the manipulators such an occiirrence could not have occurred. These 

 salmon-trout eggs arrived in Tasmania, May 5th, 1866, were placed in 

 the breeding ponds, and from them 900 fry were reared. A number, 

 Mr. Nichol* informs us, of these fry were put into a specially con- 

 structed pond, fed by a small rill of bright cool water, where they were 

 disturbed as little as possible. By the middle of October, 1867, many of these 

 prisoners had put on the smolt dress and no doubt feeling the migratory impulse, 

 leaped upon the bank in some numbers and perished. In July, 1869, they spawned 

 in the ponds. It is thus clear that this fish with anadromous instincts was 

 raised from the eggs transmitted from England, and distinctly demonstrating that 

 the number of cceca are subject to variations, so useless as a definite guide to 

 species. If, as shown, changes in climate and food can induce such a marked 

 difference, that in the Antipodes two forms of sea trout may be detected in one 

 specimen : if the anadromous forms can be traced step by step and link by link 

 into the brook-trout, or vice versa : if breeding the two forms together causes 

 no unusual phenomenon, I cannot resist agreeing with Widegren,f Malmgren, 

 Collett, Feddersen, Malm, and others, that we are dealing with a single species 

 subject to almost innumerable modifications in accordance with variations in 

 climate, locality, and food. 



Lastly, it must not be supposed that because (as stated at page 57) British 

 anadromous salmonoids possess more ccecal appendages than are normally found 

 in non-migratory trout, that such is everywhere the case. In the British Museum, 

 these appendages vary among specimens of the Loch Leven trout between 49 and 90, 

 due either to the convergence of several into one, or the subdivision of one into 

 two or more. But in this case the fish are residing in a large lake, and do not 

 appear to be many generations removed from their marine ancestry. It seems that 

 this large number in lake forms is likewise not unknown elsewhere ; thus the 

 Salmo marsilii from the lakes in Upper Austria has up to 100, S. lacustris 

 from Lake Constance, which Siebold considers the same species, has up to 74. 

 S. venemensis, Giinther, from Sweden, which Malm gives as a variety of the 

 common brook-trout has at least 62, while our larger forms of lake-trout, 

 8. ferox, have been found possessing a few in excess of those which inhabit 

 streams. 



The observations of pisciculturists and field naturalists, respecting the 

 varieties of trout and the modifications to which they are susceptible, may prove 

 most valuable in unravelling the confusion which has been imported into this 

 genus. In the following pages I have purposely omitted the enumeration of 

 some continental forms that doubtless will at a future date be abundantly 

 proved to be merely species created by naturalists, but unable to stand the test 

 of a rigorous examination carried on in an extended scale by competent inquirers. 



2. Salmo trutta, Plate CXI, fig. 1, and Plate CXII, fig. 1, 2. 



Trutta salmonata, Schonev. Ich. p. 65 ; Willughby, p. 193 ; Ray, Synopsis, 

 p. 63. Salmonata, Sibbald, Scot. no. 25. Salmo cinereus aut griseus, Willughby, 

 p. 193; Ray, p. 63. Salmo trutta, Linn. Fauna Suec. p. 347; Gronov. Zooph. 

 no. 367. Salmo, no. 3 and 5, Artedi, Synom. pp. 23, 24, Genera, p. 12, and Species, 

 p. 51 ; Klein, Pise. Miss. V, p. 16, t. v, f. 1. Sea-trout, Pennant, Brit. Zool. (Ed. 

 1776) iii, p. 296 (Ed. 1812) iii, p. 347. Bull-trout, Low, Fauna Oread, p. 222. 



Salmo trutta, Linn. Syst. Nat i, p. 509 ; Bloch, Fische Deuts. i, p. 143, t. xxi ; 

 151. Schn. p. 399; Gmel. Linn. p. 1366; Bonn. Ency. Ich. p. 159, pi. lxv, f. 263; 



* " The acclimatization of the salmonidce at the Antipodes." 

 f Lacepede considered the Salmo trutta identical with S. fario. 



