90 
ioo times heavier than that of a salmon of the same weight, and 
about 13 times heavier than a halibut’s otolith. The reason for 
the great disparity in weight between the Otolith of a Cod and 
that of a Salmon of the same weight, arises, in my opinion, from 
the fact that a Cod is a deep water fish and the Salmon is sup¬ 
posed to be a surface water fish—the former would therefore re¬ 
quire a sounding board, so to speak, of much larger dimensions 
for such a density of water in comparison to the latter. 
The haddock seems to have the heaviest otolith for its size 
in all the Gadidae tribe. The otolith of a plaice is a very beautiful 
object, showing a series of light and dark rings, by which the age 
of a plaice is easily ascertained, but the otoliths of all the Gadidte 
tribe are too opaque to be of the slightest use for this purpose. 
ADDENDUM. 
New Zealand Trout. 
For fifty years or more various attempts have been made at 
considerable expense to introduce the Salmo Salar into New 
Zealand Waters from this country. Up to the present, failure after 
failure has to be recorded, and the problem remains unsolved. 
Nothing can go better with the experiment up to a certain 
point. The hatching and the early growth of the fish are a great 
success, but when the smolts are ready for migrating to the sea, 
nothing could be worse. They migrate, but are never seen nor 
heard of afterwards. The reason for this failure can only be 
a matter for conjecture. 
The late Mr. Sclater, who was Secretary for the Zoological 
Society, was much interested in the matter, and knowing that I 
was going to New Zealand in the ’seventies, asked me to write 
him a paper for his Society, describing what I saw, and the pro¬ 
bable reason for the failure. I had every opportunity when I was 
there to go fully into details, and I came to the conclusion that 
there were two obstacles to success. In the first place the ocean 
round the coast of New Zealand is one of deep water and, as a 
consequence, the food of the salmon is wanting. The shallow 
waters which surround the coast of Great Britain, on the other 
hand, abound with fish, and thus these waters form a vast spawn¬ 
ing bed. 1 he deepness of the ocean is not the home of herring 
and crustaceans, such as the salmon has been accustomed to, and it 
comes to this, that a fish of surface habits is being introduced to a 
habitat, which is totally inconsistent with its natural state. 
Another cause of failure may be the existence of large deep 
water fish, which prey upon the young smolts at the mouths of the 
rivers. 
This then, and the want of their natural food may be the 
two chief causes of the failure to introduce the Salmo Salar into 
New Zealand 'Waters. In our home waters we have no monsters 
