The Size of Bat Families.—It is not known that bats make a nest like birds, or that they have any other way of caring for their young than by carrying them hanging to their fur whether during flight or while suspended at rest by the legs.
So we might naturally infer two things: first, that the young bats would be born in a somewhat advanced condition so as to be able as soon as possible to shift for themselves; and, second, that the number produced at a birth would be small.
The former inference would seem to be true, judging from the large size of the little bats before birth, and the rarity of the capture of the mothers with young. In one case the two unborn young weighed two-thirds as much as the parent, and the average of twenty individuals gave the weight of the young as four-tenths that of the parents.
Upon the second point it is stated by Van der Hoeven ("Handbook of Zoölogy," vol. ii., p. 731) that "bats commonly produce one or two young ones at a birth;" but he does not say upon how many observations the conclusion is based.
Prof. Owen ("Comparative Anatomy of Vertebrates," vol. iii., p. 730) Records two observations of bats (Vespertilio emarginatus and V. noctula), with each one young, and concludes that this is commonly the case with all bats.
A collared fruit bat (Cynonycteris collaris) produced a single young February 27, 1870, and a second April 7, 1871.[1]
In Jamaica Mr. Osborn observed several females of Molossus fumarius and Monophyllus poeyi, with each one young.[2]
The same observer mentions two other species (Macrotus Waterhousii, and Monophyllus Redmanii), without specifying the number of young; but we may infer that, as in the other cases, each female had but one.
In a single female of an undetermined Brazilian species I have found one young; and in each of forty females of the Nyctinomus Brasiliensis (from Brazil) a single young.
These are certainly facts in corroboration of the opinions of Owen and Van der Hoeven, but let us not be hasty in generalizing from them respecting all bats.
In June, 1874, there were brought to me twenty females of the "little brown bat" (Vespertilio subulatus). Each was found to contain two little bats in various stages of development.[3]
Finally, Prof. Putnam, of the Peabody Academy of Science, has kindly allowed me to examine two females of the Lasiurus novehoracensis taken in Massachusetts, on each of which were three young bats.
The foregoing observations indicate that, while one is the more
