Artuur.—On the Brown Trout introduced into Otago. 467 
difference in the productions of the windward and leeward groups, the only 
possible natural division of the Archipelago.” In attempting to throw light 
upon the remarkable difference in the inhabitants of the different islands, 
he points out that, as the Archipelago is free, to a most remarkable degree, 
from gales of wind, neither the birds, insects, nor lighter seeds, would be 
blown from island to island, and that the profound depth of the ocean 
between them and their apparently (in a geological sense) recent volcanic 
origin, rendered it highly unlikely that they were ever united, a considera- 
tion far more important than any other with respect to the geographical 
distribution of the inhabitants of the group. 
But although certainly less striking than that of the Galipagos, the New 
Zealand case, when carefully examined, and taken with especial reference 
to the very narrow strait which separates the two islands, and the proba- 
bility that they were once united, is one of great peculiarity, masked how- 
ever by the greater extent of the flora, and of the number of orders repre- 
sented in proportion to the number of genera and species of each. 
Without going more at length into this subject, which miglit be 
wearisome, I think I have shown sufficient to excite the attention of 
naturalists, and to induce such observations as may help us to a clue to the 
special causes, which, under the law of natural selection, have brought 
about these remarkable results. 
Art. LV.—On the Brown Trout introduced into Otago.—Paper No. 2. 
By W. Arrmur, C.E. 
[Read before the Otago Institute, 13th November, 1883.] 
: Plates XLIII. and XLIV. 
Tue first paper of this series I read to this Institute in 187 8,* and the results 
of my observations continued since then I now propose to lay before you. 
My chief object in so doing is to record the effects (if any) consequent on 
the acclimatization of trout (Salmo fario) in our waters; on their growth, 
habits, and strueture, as bearing on the theory of the variation of species. 
Dr. Francis Day, late Inspector-General of Fisheries for India, has made 
publie his investigations on trout in England,—carried out about the same 
time as my first observations, —and which bear out, to a great extent, the 
fact that the anatomical distinctions laid down by Dr. Giinther in his cata- 
logue, between some of the species of Salmonidw, are not altogether to be 
depended on. Professor Huxley also has recently commenced an examina- 
tion into the distinguishing marks of the young of the British Salmonide,— 
* See Trans, N.Z. Inst., vol. xi., art. xxiv, 
