94 VESPERTILIONID^— NYCTALUS 



caught emerging for her morning flight, one hour and twenty- 

 six minutes before sunrise. 



" Having made sure of my specimen, I quickly removed the 

 net so as not to disturb the remaining inmates of the hole in 

 their egress. I failed to see any bats emerge — the light being 

 too dim — but at 4.20 had the satisfaction of seeing one re-enter. 

 As this individual cannot have left the hole while the net was 

 over it, the duration of its flight had not exceeded sixty-five 

 minutes. 



" In the evening of the same day I saw four bats (the 

 survivors of the colony of five) emerge for their evening flight 

 in quick succession between 7.38 and 7.42, 6 and 10 minutes 

 after sunset; and at 8.53 by a fortunate chance, the moon's 

 rays falling full on the line of flight at the moment, I succeeded 

 in seeing one go in. This was one hour twenty-one minutes 

 after sunset. As the interval between earliest and latest 

 emergence had been so short, the duration of this example's 

 flight had been told with some exactness. It cannot have been 

 on the wing for a longer period than "j^, or a shortei'- one than 

 71 minutes. 



" We may thus claim to have a set of data, limited in 

 number, but precise as far as they go, determining the flight- 

 time of this local and somewhat imperfectly studied species. It 

 has an evening flight and a morning flight, the two being of 

 about equal duration. The evening flight is usually commenced 

 a little earlier than 15 minutes after sunset, the average of 

 seventeen actual emergences noted being I3|- minutes, the 

 earliest i minute, the latest 23 minutes, and the mean between 

 the extremes 1 2 minutes after sunset. The bat returns at night 

 to the same hole as serves it for a sleeping apartment by day ; 

 the precise time of its return, in the only instance noted, having 

 been 81 minutes after sunset. Its moment of leaving the hole 

 in the morning has also been noted only once, in the case of 

 the specimen caught on August 13th; but it should be 

 remembered that this individual must have been the Jirst to 

 emerge on the date in question, and therefore the usual time 

 of emergence is probably a little later than 86 minutes before 

 sunrise. The time of going home in the morning, on an 

 average of five observations, is 26 minutes before sunrise, the 



