Growth and Development of the Salmonidcz. 171 



water, together with high feeding, have 

 caused a rapid development and growth of 

 these fish, especially the Salmo trutta, which 

 are much farther advanced than fish of the 

 same age in England ; although the milt in 

 the males which were examined was not yet 

 developed. The Tasmanian fish above re- 

 ferred to were about 11 months old when 

 examined on the 1st of August, 1878. 



It is a curious circumstance that while 

 Australians are endeavouring to introduce 

 the different varieties of the salmonidas at 

 the antipodes, none of which existed there 

 naturally, this family of fishes, so valuable 

 to the human race, has been threatened with 

 extinction in the Old World by a new disease 

 which has attacked the salmon and trout in 

 some of the rivers of Scotland, and in the north 

 of England. It is stated that the same disease 

 has also appeared in California. It is said to 

 be caused by a fungoid growth of an orange 

 colour, called saprolignia ferox, which attacks 

 the fish and eats its way to the bone, speedily 

 causing the death of the fish. Pollution of the 

 rivers from manufactories, and overstocking, 

 have been assigned as causes of this pest. 



