1893.] Evolution in the Genus Megascops. 645 
central Texas having a mean temperature of 65? Fahrenheit 
and upward for the months mentioned; another on the north, 
extending from New Brunswick to Central Dakota, 45? Fahren- 
heit and less, marking the distribution of the gray form, while 
the intermediate territory lying between the isotherms of 45° 
and 65? covers nearly the entire area inhabited by the reds. 
Just how this influence is exerted it is, of course, impossible to 
say, but that there is an apparent relation is evident from a 
comparison of maps 2 and 4, while maps 2, 3, 4 and 5 show 
that on the northern and southern borders all influences com- 
bine to produce the existing conditions. 
In comparing the northern belt, where a minimum degree 
of temperature exists coincident with the gray phase with the 
southern, where a mazimum degree is found also coincident 
with the same phase, the question arises—Why, in one portion 
of the country, is a low temperature and in another a higher 
temperature conducive to a given phase? and the problem is 
a knotty one. Future investigations may show that some 
cause or causes, still unknown, exist along the Atlantic coast, 
but the probabilities are that humidity is the dominant factor 
in the subject under discussion. 
e C—INFLUENCE OF ACQUIRED CHARACTERS. 
In attempting to ascertain the causes influencing the condi- 
tion of Megascops, one of the foremost things to be considered 
is the peculiar distribution of sex as regards color. Leaving 
the intermediates out of the discussion, as being an evident 
attempt on the part of nature to fashion a form midway 
between the two color phases, it will be best to consider only 
the gray and red. . 
Out of the total of 3600 birds which furnished data for this 
paper, 646, scattered over the entire territory, show the follow- 
ing relation of color to sex. It will be seen that the number of 
gray males far outnumber the red males, while the number of 
red females outnumber the gray females four to one. This is 
scarcely a fair average for the whole, as it must be borne in 
mind that the numbers cover all of the territory inhabited by 
the three forms—asio, floridanus and mecallii—and conse- 
