208 | Colors of West Coast Mammals. oe [Zon 
lies ie line ae aptelacest pieniones to the. species. This tendency 
might be termed the Law of Sexual Intensification. It can by no : 
~ means be considered a universal law, but it might be found useful 
in explaining more fully many cases of bright or dark col as 
birds and mammals. And the cases to which it would apply 
not be simply those in which the male was more intensely colored 
than the female. There must be a limit to the development of every 
color—a point at which it reaches its maximum of intensity. When 
the male has reached this goal, if the color be. of general utility to 
the species, the tendency of the characters of one sex to cross over 
to the other will in time cause the female to assume a color identical 
with that of her mate. 
The black hare (Lepus znsularis) found by Mr. Bryant on Es- 
piritu Santo Island, in the Gulf of California, is a case very similar 
to the one above considered. Mr. Bryant says that it also is found 
in a region of black volcanic rock where its colors are completely 
protective, and that the only time when specimens could be secured 
was when they came down on the light sand of the shore where 
they were very conspicuous. In this animal, however, the evolu- 
tion is very complete. Being an insular form it has been com- 
pletely isolated, and the black has extended over the entire upper 
parts of the body. In the small series available for examination 
there is no appreciable difference between the sexes, and it is prob- 
able that the female has overtaken the male as previously explained. 
On the sandy mainland and adjacent sandy islands, a very pale 
form of Lepus occurs, which may in the light of more ample material 
be found to be a separate variety. This suggests the question of 
how toaccount for the paler forms of the genus, for a law of in- 
tensification could be of no service in such a case. The direct 
action of the environmentseems to be the most reasonable hypothesis, 
although of course it would be no longer tenable if the non-inherit- 
ance of acquired characters should be proved. Examples of the 
remarkable bleaching power of sunlight are common. Animals. 
living in a sandy or desert region constantly exposed to the sun’s 
rays would become somewhat bleached. Those individuals which 
were the most affected, or were affected so that their colors were ~ 
most in harmony with their environment, would have the greatest — 
chances of survival, and, granting that acquired characters can be — 
inherited, would be the parents of a paler colored race. Thus in 
