652 THE POPULAR SCIENCE MONTHLY. 



common number of young produced by bats, two and three may 

 occur. More extended inquiry may show that these larger families 

 are less rare than now appears, and even that as many as four young 

 may be produced at a birth. For while bats are usually credited with 

 only two nipples, an extra pair exists upon the Lasiurus novebora- 

 censis. 



The uniformity in number with each species is very striking. 

 Twenty-two of one species had each two young, while forty of another 

 had each one. 



In the former case the young were placed one on the right and the 

 other on the left of the body. But in the latter case the single young 

 was invariably on the right side ; while, in the single specimen of the 

 undetermined Brazilian bat, the young was on the left side. 



Equally striking with the above facts is the isolation of the females 

 with young. Among forty-three Nyctinomus Brasiliensis was but a 

 single male. No males were found near the twenty-two Vespertilio 

 suhulatus. Osborn says that, of Molossus fumarius, all of one large 

 lot were males; while at another time, in a large hollow tree, he found 

 in one cavity about one hundred males, and in a second about the same 

 number of females, with " apparently a few males here and there." 

 ' Evidently there is much to be learned respecting the domestic and 

 social economy of these animals. Perhaps the males gather food for 

 the females.' 



Perhaps the most important fact, from a practical point of view, 

 is that of the power of the mother-bats to carry such a weight of 

 young in addition to their own. Yet, so far as I know, all estimates 

 of the extent of wing and size of muscle, which would be necessary 

 to enable a man to fly, have been based upon the idea that the only 

 flying mammal is a fair standard.^ 



These estimates should be corrected so as to conform to the fact 

 that a bat can fly with nearly double its ordinary weight. Even this 

 may not encourage us to hope for a future race of flying-men. But it 

 renders it worth considering whether a man, naturally slight of frame, 

 with small head, could not so far reduce his weight by a flesh diet, and 

 by the amputation of his legs, as to enable him, by special cultivation 

 of his pectoral muscles, to work efi^ctively a pair of wings less exten- 

 sive than those now supposed to be required. 



' The writer has not been able to examine the development of bats with the nasal 

 appendages. He would be glad to receive information upon the habits of bats with young, 

 and to exchange the latter for specimens of Amphioxus. 



^ Harting (" Archives Neerlandisches," iv.) calculated that a bat the size of a man 

 would require wings two and a half metres long, and with a surface of one and a half 

 square metre. 



