Ricers of Scotland into Tasmania. 137 



the numbers gradually decrease. He says that the male 

 and female fish unite in selecting a spot in the stream, and 

 together excavate the ground from that spot to a sufficient 

 depth for the reception of the spawn, the depth varying from 

 9 to 18 inches ; that the female deposits therein part of her 

 ova, which the male immediately impregnates with the milt ; 

 and that the fish continue to enlarge the bed, and at same 

 time cover the seed already deposited with the gravel from 

 the bed thus extended. It appears that the length of time 

 between the deposition and hatching of the ova depends 

 entirely on the temperature of the water— varying from 90 

 to 100 days. 



When first hatched, the fish average about f of an inch 

 in length, and have a kind of conical bag attached to the 

 belly, wdiich provides them with sustenance during the first 

 five weeks of their existence. After that period, the contents 

 of the bag being exhausted, the fry have to find their own 

 food : they gradually assume more of the natural outline of 

 the grown fish, and improve very fast ; so that at the end of 

 two months we have a perfect fish, marked with transverse 

 bars, and furnished with distinct fins. From these bars 

 alone arose many arguments against these fry being the 

 young of the Salmon, — for it was said that the fishes so 

 marked were Vans, and that the young of Salmon are 

 enveloped in their silvery coating when hatched, and so 

 continue through all their after ages. Mr. Young and 

 others have now, I think, very clearly proved that, when 

 the fish is about 11 months old, nevf scales and silver 

 coating begin to appear, the transverse bars look more and 

 more dimly through this scaly covering, and the young fish 

 have fairly entered upon another wonderful and interesting 

 change, which advances rapidly towards perfection. At 

 the end of 12 months the fish are completely enveloped in 

 their silver coating, aud the transverse bars have entirely 



