206 | Transactions. —Zoology. 
Occasionally, but not often, we have found a female give eggs of a light 
straw colour, and these have hatched out quite as well as those of the 
ordinary hue, with no difference in time, or in the appearance of the fry. 
On August 28th, 1880, we had in the hatching boxes at Opoho, ova of this 
colour from two females of 5lbs each, it was also much smaller than the 
pink ova from equally heavy female trout. This peculiarity in colour has 
been observed to occur sometimes with trout in English rivers, as mentioned 
by Mr. Frank Buckland, in his book on ‘“‘ Fish Culture.” In this last 
season’s stripping one female gave 30 eggs much larger, twice the diameter 
of her other eggs, and as big as Californian salmon ova. They were of a 
light violet colour, and most hatched out, but 17 only survived, and these 
are thriving well and are kept by themselves. Her other ova were of the 
usual size and colour. 
As to the number of ova produced by our trout, we find it to be 800 to 
1000 for every pound weight of the fish. 
Hatching bowes.—The hatching boxes and house, dam, and ponds for the 
young fish, are on the banks of the Opoho Creek, at the north end of Dun- 
edin. The place is awkward of access, but excellently chosen as regards 
coldness of water and protection from the sun’srays. The creek, flowing as 
it does down the shady side of Signal Hill and through bush, is cold, but 
has a considerable quantity of vegetable matter in solution (see analysis given 
above); not too much, however, as we have found, by the health and success 
attending our young fish, reared in it. The arrangement of these breeding 
ponds and the water supply is shown by a diagram which I have made to 
accompany this paper (pl. XIV). The water passes from the dam through a 
small fluming of timber four inches by four inches, past the hatching house 
to the fish ponds, and after flowing through these is allowed to discharge 
into the creek. At the hatching house a small pipe connects this fluming 
and the filter-box. The filter-box consists of two chambers, into the first 
of which, containing the filtering materials, the water flows from the box 
fluming. The water then passes through the bottom of the partition into 
the second chamber, where it rises and is drawn off by the several pipes 8 
wanted, which supplies the hatching boxes. These boxes, twelve inches by 
six inches, built of planks one inch thick, and from four to seven feet long, 
are placed in parallel rows on either side of the hatching house. Each has 
sufficient inclination given to it to secure a gentle flow of water, the water 
passing through a zine grating from one box to another. Clean gravel 
about an inch deep, being the debris of trap rock from the Opoho Creek, 
covers the bottom of each box, and the water, to the depth of two inches, 
covers this layer. The hatching house is boarded with Hobart Town 
palings, and has a calico or scrim roof resting on battens. — 
