VESPERUGO NOCTI VAGANS. 
93 
killed on the first evening of their appearance averaged 90mm. in 
length by 261mm. in stretch, but weighed only half as much as 
their parents. The adults average about 104mm. in length by 
302mm. in stretch. When on the wing the young may be dis- 
tinguished from the old by the weakness and hesitancy of their 
flight, rather than by the difference in size. The young are much 
more beautiful than the adults, and they alone possess the perfect 
silvery tips to the hairs from which the species derives its name. 
Even before going into winter quarters their soft silvery backs 
have given place to the grizzly coats that characterize the adults. 
My esteemed friend, Mr. William Brewster, has kindly favored 
me with the following very interesting account of a colony of bats 
that he discovered during an ornithological excursion into the ex- 
tensive coniferous forests of western Maine : — 
“ On June 18, 1880, I was searching for woodpecker’s nests 
among the stubs that line the shores of Lake Umbagog, when I 
noticed a small ragged-looking hole about two feet above the water 
in a trunk that stood well out on the flooded meadows. I should 
hardly have turned aside to examine it had I not fancied that I saw 
something move at its entrance ; accordingly, paddling to the spot, 
I struck the tree sharply with the butt of an axe. The blow was 
followed, not by the appearance of a woodpecker’s or nuthatch’s 
head, as I had expected, but by an outbreak of shrill squeaking 
sounds that seemed to come from every part of the interior. As 
have been born within forty-eight hours. The single one, a male, weighed noo milligrammes, 
and measured 43mm. in length by 79mm. in extent ; the cord measured 20mm., and the placenta 
10x14mm. One of the other females contained twins, both of which were females ; one of them 
weighed 1380 milligrammes, measuring 41mm. in length by 72mm. in stretch; cord 18mm. ; 
placenta 9x14mm. The other weighed 1100 milligrammes, and measured 39x68mm.; cord 17mm.; 
placenta 8x13mm. That the young are brought forth in the southern part of the State at about the 
same date as with us is evidenced from the following. Dr. A. K. Fisher states that a female which 
he killed at Sing Sing, in Westchester County, June 24, 1881, “contained two young, well de- 
veloped, and probably would have been delivered in a few days. The young each weighed 1,45c 
milligrammes. On removing the amnion the ears of one of the young bats became erect. The 
placenta of this species is different from that of the Little Brown Bat ; instead of being circular it 
is elliptical, measuring 10 by 15 millimetres.- The placentas were attached to the posterior wall of 
the uterus near the summit of each cornu. The umbilical cord measured twenty millimetres in 
length.” (Forest and Stream, Vol. XVI, No. 25, July 2t, 1881. p. 490.) 
