178 MAMMALIA. 



is nearly an hour of twilight, the silver-haired and little brown bats 

 begin to fly shortly after eight o'clock, but the present species is 

 seldom seen till half an hour later, and those we killed were common- 

 ly shot about 9 r. m. As the season advances and the evenings be- 

 come shorter, all bats, of course, appear proportionately earlier. On 

 the 3d of August I shot Atalaplia cincrca at eight o'clock, and on 

 the 8th of October at precisely 6 o'clock — three hours earlier than 

 the same species was killed during the first part of July. 



In warm evenings it was not to be seen at all, and I have never 

 observed it when the temperature was above 1 5*-' C. (69^ F.). It was 

 most often seen when the thermometer ranged from lo"^ to 12^ C. 

 (5o° to 53.6'' F.). Assuming that the species does not leave its 

 hiding-place when the temperature is above i5^ or i6'"*C. it might 

 be supposed that it would suffer for food if there were several suc- 

 cessive warm evenings. But it must be remembered that the coolest 

 part of the twenty-four hours is just before daylight, and throughout 

 the northern regions inhabited by this species there are few days 

 when the temperature does not fall to i5'^C. in the early morn- 

 ino-. Moreover, it is well known that most bats are as active 

 just before daylight as in the evening. Hence, if the evenings 

 are too warm for its comfort, it would almost always be enabled, 

 by the falling temperature, to sally forth at some later hour of the 

 night. 



The Hoary Bat occurs about the Red River settlement in British 

 America, and Dr. Richardson obtained it at Cumberland House on 

 the Saskatchewan, in lat. 54^' N. * Robert Kennicott procured it 

 in the Hudson's Bay Company's territory, farther north than any 

 other species of bat has been taken. It is a summer resident of 

 high latitudes, its southern limit in the east coinciding, apparently, 

 with that of the Canadian Fauna. In the west it has been taken 

 in Arizona and New Mexico, but only, so far as I am aware, at 

 considerable altitudes. In the fall and early winter isolated indi- 



* Fauna Boreali Americana, vol. I, 1S29, ji. i. 



