248 Proceedings of the Royal Society 
Lewis, which is of so much interest in connection with this subject 
that I append it to my communication : — 
“ From what I saw and heard from you, I am convinced that the 
disease from which the salmon in the Grimasto river in Lewis 
suffered some eleven years ago differed from the one you are now 
investigating. In the first place, we had no trace of fungus , — the 
affection was confined to the head, and although it destroyed many 
fish yet very many recovered from it. It attacked the fish in the 
sea, or, according to my theory of its origin, in the brackish water 
between the sea and the mouth of the river. It assuredly had not 
its origin in the river, or in the loch above it. There are many 
brown trout in our rivers and lochs, and none of them suffered. 
Neither among the multitudes of sea trout about us did I see one 
affected. The disease I am speaking of appeared about the middle 
of the season of 1868. As happens frequently in the Lewis, the 
months of May and June had been very dry, and for weeks before 
rain came, some time late in July, the fish had not been able to get 
up the river in consequence of want of water at its mouth. We 
were told that many fish had been found dead in the bay, and after 
rain had fallen and we were able to fish in the river and lochs, we 
then saw the nature and extent of the disease. Fish were found 
dead and dying in the river and at its mouth ; others not too far 
gone, took the fly, and were caught. On the dead fish examined 
the whole of the upper part of the head was found covered with 
ecchymosed spots and ulcerated, the ulcers more or less superficial, 
and some with everted edges. In some the cartilages of the nose 
had been attacked, and one side of it cut out as it were by a cor- 
roding sore. When cut into, the bones and cartilages of the head 
were found to be softened, and there were marks of inflammation in 
the brain and membranes. The eyes were natural, the gills pallid 
but otherwise sound, and none of the fins affected. In the far 
advanced cases, among the fish caught, the softened appearance was 
very much the same, whilst in those less diseased the ulcers were 
few and small, the rest of the head being simply ecchymosed. In 
a great many fish recovery apparently soon commenced, the ulcers 
began to cicatrise, and the fluid in the ecchymosed spot was almost 
altogether absorbed. In every case, I may say, we observed the 
gill covers had a dull, white, leprous appearance, and in all the fish 
