1880.j natural sciences of philadelphia. 133 



March 9. 

 The President, Dr. Rusohenberoer, in the chair. 

 Twenty-three persons present. 



Mammary Glarids of Bats. — Dr. H. Allen exhibited specimens 

 of bats dissected to show the position and peculiarities of the 

 mammary glands. These bodies have been described as post- 

 axillary and two in number. For Desmodus this account is cor- 

 rect. For PhyUorhina^ Nycferis and the common red bnt of this 

 country {Atalapha {-^ Lasiurvs) novehoracensu) it is incorrect. 

 In the first two the glands answering to the axilla are low down 

 and have their nipples on a line with the middle of the clavicle. In the 

 common red bat the gland answering to the so-called post-axillary 

 is outside and below the axilla, but on a line with it. It occupies, 

 indeed, the lower third of the side of the chest and borders upon 

 the inferior line of the chest. In addition to this there is con- 

 stantly present a pectoral gland situated as in Quadrumana and 

 the human species. These glands resemble one another in general 

 appearance and size, being circular in form, without hair, of a 

 dull yellow color, possessing a well-developed nipple, and meas- 

 uring 3 lines in diameter. 



It is interesting to observe that the specimens of non-lactating 

 bats show no external signs of mammse. The mammary regions are 

 covered with fur of the same character as seen elsewhere. 

 Neither in a female with embryos 2 lines in length is there any 

 external development. If such a specimen be dissected, the 

 locality of a rudiment of the gland can be detected by the posi- 

 tion of a small circle of thin, dark skin with a central white spot, 

 such structures representing the patch of modified skin and nipple 

 ready to receive the future developing active gland. No mam- 

 mary structure in this stage is anywhere visible, nor is there any 

 subcutaneous fat. Dissection of the body of the lactating female 

 on the other hand shows the mamma to be as large as the external 

 conformation, and the pectoral and lateral thoi*acic regions to be 

 occupied by a large but sharply limited mass of fat, which runs 

 up into the axilla and encroaches upon the dorsal surface of the 

 trunk. The rest of the under surface of the animal is without fat. 

 It is likely that there exists in the bat the same provision noted 

 in analogous structures of many lower animals, — namely, the 

 presence of secondary sexual characters (among which the milk 

 gland may be placed) which practically disappear in the periods 

 between sexual activity. 



