ArtHur.—On the Brown Trout introduced into Otago. 469 
Hill. From this line, southwards to the coast, the rivers rise among older 
or trap formation, and flow more or less through a wooded country. Anfong 
the former, as a rule, the higher parts of the rivers are rock-bound, while 
the lower reaches and mid portions pass over alluvial flats, the shingle and 
gravel in their channels being the débris of their parent rocks with more or 
less quartz pebbles and fine sand. Among the latter class the gravel is 
almost wholly trap with a little quartz, while very few streams among either 
have beds entirely of clay or loam. A great number, especially of our 
smaller rivers, are rock-bound in their entire course, and so, having a scanty 
supply of gravel, are deficient in breeding capabilities ; but perhaps two- 
thirds of all the rivers are well adapted for spawning, so far as gravel and 
sand can contribute to that end. One curious exception, however, must not 
be overlooked here, viz., the Water of Leith, which, possessing a rocky 
channel full of voleanic boulders, particularly in its lower course, and a 
scanty supply of gravel, yet for several years subsequent to 1874, when it 
was opened to anglers, produced an astonishing number of trout. It has 
not maintained this character, but that is due to excessive fishing and 
poaching. Rivers to the west of the Mataura are not included in the above 
references, as the stocking of these has not been kept up; and I have only 
examined one trout taken there, viz., from the Oreti, a snow-fed water. 
The banks of the rivers are very much yet in their natural state, covered 
by native grasses, and in some cases, bush ; but cultivation has overtaken 
all the lower plains of the main streams to within a few yards of the water. 
Cultivation no doubt affects the character of the food-supply, and quantity 
also ; so do grass fires around the upper waters, while both lower the mean 
flow of water in the rivers, directly and indirectly, also causing floods to 
become much more violent, high and mischievous, although shorter in 
duration than they used to be. During a residence of twenty years in Otago 
I have seen quite enough evidence of the latter of these facts, as for example 
in Shag Valley. 
The mouths of the principal rivers which enter the sea directly have 
estuaries, protected by sandy bars. In the case of the Kakanui, Shag, and 
Waikouaiti Rivers the tide has a course of a mile and a half or more, 
upwards from the sea; while the tidal way of the Mataura may be estimated 
at five miles at the very least. Some of our best trout streams do not 
discharge directly into the sea, but are feeders of larger rivers, having tidal 
estuaries. So much then for a general definition of the geological conditions 
of our trout rivers that relate to distribution. 
It only remains in this connection to mention that the lakes into which 
trout have been placed are the Wakatipu,’ Wanaka, Hayes Lake, Waihola, 
and Tuakitoto. The surroundings of the three former of these lakes are 
