108 
THE CALIFORNIAN SALMON. 
the salmon and the trout are of rare occurrence in their 
natural state, but by artificial impregnation this has often 
been effected. I have failed, however, to find any record 
of hybrids from this cross, having been proved to be fertile. 
There are certain characters, which are found to be con- 
stant in numbers of individuals, and which are relied upon 
for identification of the species. These are : — the form of 
the bones of the cheeks and jaws ; the size, arrangement, 
and permanence, or otherwise, of the teeth ; the form and 
development of the fins ; size of the scales indicated by the 
number of rows above and below the lateral line ; the 
number of the vertebrae, and of the pyloric caeca, which are 
sac-like appendages to the main gut, which is short and 
simple. 
There are other characters, which are found to be 
variable, and little reliable as a means of identifying the 
species, such as the number of the fin rays ; the colour, 
form, size, number, and position of spots and bars, or parr- 
marks. Although the parr-marks, or transverse bars, are 
common to all the individual species of the genus, it has 
been observed that the migratory species have two or 
three more, than the non-migratory kinds. The males 
attain brighter colours than the females, as the spawning 
season approaches, while the young of the different 
migratory species put on a coat of silvery scales, which 
covers the bluish transverse bars, before they commence 
their migration to the sea. 
The colour of the bottom of the water in which the fish 
live, as well as that of the water itself, influences greatly 
their appearance and markings, and, like the chameleon, 
they have the power, to some extent, of changing their 
colour in accordance with their surroundings. 
The size of the fish is also a very variable character, and 
cannot be relied upon as a guide to its identification. It 
