NATURAL HISTORY OF BRITISH SALMONIDM. 139 



Palace in 1859, several were actually matured, it is stated, in 

 as little as thirty days. 



The actual bursting of the young salmon from the egg, which 

 I have often watched, takes place thus : The fish lies in the 

 shell coiled round in the form of a hoop ; and the greatest 

 strain being at the back, it is at this point that the shell splits 

 across. After a few struggles, it is completely thrown off with 

 a jerk leaving the red yolk of the egg, by which the fish is 

 nourished during the first five or six weeks of its existence, 

 suspended in a conical bag under the stomach. At this ' bag 

 stage ' of its development the future monarch of the stream is 

 represented by a mere ragged line, fringed at the edges and 

 almost transparent, the head and eyes being prominent and 

 altogether out of proportion to the body, which measures only 

 about five-eighths of an inch in length, and is of a pale peach- 

 blossom or azure tint. In thirty-five or forty days after hatching 

 the yolk bag disappears, and the fry becomes a perfect little 

 fish of about an inch long with the fins separated and properly 

 developed, and the tail deeply forked at the end. The general 

 colour now also changes to a light brown ; and the sides are 

 indistinctly crossed by nine or ten transverse dusky bars, or 

 parr marks, characteristic of all the species of salmon and trout 

 when in an immature state, and which in the true salmon 

 remain more or less visible even in a smolt or parr six inches 

 long. 



The differences in appearance between the fry of the salmon, 

 bull trout and sea trout, and probably also between the fry of 

 the other allied species of the genus, are so trifling as to be 

 scarcely perceptible, and are, moreover, liable to variations 

 with local circumstances. 



The young salmon fry are unable to move about very freely, 

 owing to the presence of the vitelline, or yolk bag, which im- 

 pedes their motions in swimming, and obliges them when at 

 rest to lie perpetually on their backs, unless artificially sup- 

 ported. This support they seek to obtain by placing themselves 

 amongst gravel or in crevices between stones, exhibiting generally 



