426 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



from No. 105586, an adult female of L. hlosseviUei. The embryos 

 are all united by shreds of membranes and uterus, so that there is no 

 doubt they came from one parent, A specimen of L. horedlis from 

 Illinois (No. 14273), preserved in alcohol contains two fetuses. 



The most interesting specimens in this connection are Nos. 114044-48, 

 an adult female nursing four young, brought into the National Museum 

 alive by Mr. J. C. Lawson, of Washington, District of Columbia, on 

 June 18, 1902. Photographs of the living family were secured shortly 

 before the mother's death and are reproduced in Plate XVII. A young 

 one was at each of the adult's nipples, where it held on with great 

 tenacity, having in its mouth a good deal of its mother's hair into 

 which its hooked milk teeth firmly caught. As Dobson has suggested, 

 it is probably for the purpose of holding securely to their mothers 

 that the milk teeth of bats differ in form from those of other mam- 

 mals. 



The following table shows the weights (taken while living) and sizes 

 of the family. It is seen that the young ones were less than a third 

 grown as to weight and about half grown as to linear measurements. 

 The combined weights of the four young amounted to 12.7 grams, 

 while the mother weighed but 11 grams. 



Mother and young of Ldsiurus borealis. 



No direct observations have as yet been made on the breeding of 

 Lasiurus cinereus and Dasypterus intermedins^ and there are no exam- 

 ples of pregnant females of these bats in the National Museum collec- 

 tion, but it seems safe to predict that when the right material is 

 obtained and good observations made it will be found that the females 

 of these species bring forth as manj^ young at a birth as do those of 

 the Lasiurus Tforealis group. 



EXPLANATION OF PLATE XVII. 



All the figures are reproduced from photographs taken by Mr. Dodge, of the 

 department of photography. 



Fig. 1. Lasiurus borealis, from Washington, District of Columbia, mother with 

 four young (Nos. 114044-48) photographed while alive, lying on her back. The 

 interfemoral membrane is held out to prevent her from partly covering the young 

 with it. About seven-eighths natural size. 



Fig. 2. The same, mother with the four young attat^hed hanging from a twig. 

 About three-fourths natural size. 



Fig. 3. Dastjpterus intemedius, adult female in alcohol (No. 59533), showing the 

 two mamma' of the left side. The hair has evidently been worn away from around 

 the nipples by nursing young. About five-sixths natural size. 



