November, 1903.] 



KNOWLEDGE. 



259 



position in which the young bat supports itself when its 

 parent is iu flight does not appear to be I'ecorded ; but 

 when in repose, in the case of fruit- bats, or " flying-foxes," 

 at any rate, the baby bat hangs head-downwards on its 

 mother's chest, as is well shown in a figure published 

 some years ago in the Proceedings of the Zoological Society 

 and reproduced in the " Royal Natural History." 



By the older oljservers it was generally considered that 

 bats commonly produced two young at a birth, as is 

 testified by Pliny, who wrote that the female carried her 

 twin offspring about with her (geminos infantes seciim 

 deport at). Later observations, however, led to the con- 

 clusion that this idea was erroneous, and that as a rule 

 only one is produced iu a birth. For instance, in the 

 second edition of Bell's " British Quadrapeds '' it is stated 

 that " the examination not merely of British species, but 

 of a great number of foreign ones, has convinced us that 

 where more than one young one is produced it must be 

 regarded as an exception to the general rule." 



In an earlier passage of the same work occurs the 

 following statement : " The female bat brings forth one or 

 two young at a birth, which she nurses with great tender- 

 ness and care, carrying it about with her, and holding it 

 enshrouded in her amjile cloak, which preserves it from all 

 intrusion." Apart from the question whether the grammar 

 in this quotation is as accurate as it might bi', it will be 

 noticed that the author confines himself to the statement 

 that the mother bat carries a single offspring about with 

 her. What becomes of the other, iu the case of twins, is 

 not stated. 



The late Dr. Gr. E. Dobsou, iu his time the greatest 

 authority on bats, noticed that in certain species of fruit- 

 bats the nipples of the males were much enlarged during 

 the breeding season; and from this circumstance. he started 

 an entirely novel idea, which is expressed in the following 

 sentences : — 



" It is probalile that where two young are boi'n at a 

 single birth, the male relieves the female of the charge of 

 one (as the weight of two might render flight difficult or 

 impossible), and at the same time performs the office of a 

 nurse. It is well known that many species of bats have 

 occasionally two young at a birth, but I have never found 

 a mother with more than one clinging to her body. The 

 si/0 of the pectoral teats in many male specimens (though 

 in none yet observed by me so large as in this species 

 and iu another case referred to above) led me to think 

 that instances of the male performing the office of nurse 

 are ])robably not uncommon among bats." 



Whether this suggestion is true in the case of fruit-bats 

 must be left for future observation to determine ; but it is 

 now practically certain that it will not hold good for the 

 ordinary insectivorous bats, although, so far as I know, no 

 case has hitherto been recorded where a female of any of the 

 European species of bats has been actually seen carrying 

 about ber twin offspring. Tlie interest that would attach 

 to a well-authenticiited instance of this nature may be 

 commended to the attention of the readers of Knowledoe. 



If, however, instances of female bats carrying more than 

 one baby offspring clinging to their bodies are unknown in 

 Europe, they have recently been brought to light in 

 America. And iu these instances not only has the parent 

 bat been seen loaded with the weight of twins, but 

 actually with that of a quartette. 



Till tlic date of tlie aforesaid discovery (to which brief 

 allusion has been previously made in our " Notes " column), 

 it was the universal belief that bats never produced more 

 than two offspring at a birth. In the spring of 1902 the 

 female of a common species of American Ixit {Lnaiurui' 

 liin-fidi^) was, however, received at the British Museum, 

 accompanied by a quartette of young ones, which were 



stated by the collector to be her own progeny. In men- 

 tioning the circumstance, the descnber of this specimen 

 (which happened to belong to a new variety) very wisely 

 refrained from giving it full credence until further 

 testimony was forthcoming. 



Such evidence was not long in appearing ; and it is now 

 definitely known that not only Lasinrus borealig, but other 

 species of the same genus, and probably those belonging 

 to the allied Basypterus, are iu the habit of generally pro- 

 ducing four young ones at a birth. And, what is more, 

 these four young ones are habitually carried about by the 

 female, although no one has apparently yet taken one of 

 these bats thus loaded in actual light. It was in June, 

 1902, that a female horealis was brought to the United 

 States National Museum with her family of four still 

 cUnging to her body ; and she was successfully photo- 

 graphed shortly before her death, one of these photographs 

 being rejjroduced in the accompanying illustration. 



Bats of the genera Lasiurus and Dasypterus, it is iu- 

 tei-esting to notice, differ from the majority of their kind 

 in being provided with four nipples; and in the case of 



I'Vmale and Young of Bough-tailed Bat. 



the fenuxle brought to the New York Museum a young 

 bat was tightly holding on to each nipple by its curiously 

 hooked teeth, "aiding its grip l>y including a tuft of its 

 mother's hair. European bats„on the other hand, have 

 but a single pair of nipples, from which it may lx> inferred 

 that they never produce more tliau two at a birth. That 

 such twins, when they occur, are, however, carried about 

 by their mother, may be regarded as practically certain. 



In the case of the New York specimens, the weight of 

 the female was 11 grams, while the combined weight of 

 the four offspring was 12'7 grams. At the time the young 

 were less than one-third grown, and they would evidently 

 have remained fiU' a further jieriod with their p;weut. 

 How she coiUd have managed to tly at the date of observa- 

 tion — let alone later on — with a burden exceeding her own 

 weight, is a mystery. And yet there is little doubt that 

 she must have been capable of flight when thus laden, as 

 otherwise she could not possibly have procured food, unless, 

 indeed. su|>plies were brought her by the male, which is 

 highly improbable. 



