Prof. Reiuhardt on Emballonura cauina. 387 



wing being spread, it lias the form of a longitudinal fissure, 2 

 lines long, which extends immediately to the free outer edge of 

 the membrane, is provided with thick lip-formed edges, and leads 

 into a small cavity stretching itself along the margin of the alar 

 membrane inwards to the body, becoming more and more narrow, 

 and ending at length about If line from the fissure. The wing 

 being extended, the two lips of the aperture glide from each 

 other, so that the cavity opens ; but when the wing is at rest or 

 only half-extended, the innermost, that is to say, that lip which is 

 nearest to the body, glides over the outer lip and thus covers it. 



Besides this, the small bag is provided with particular muscles, 

 on the contraction of which it must open ; for in the alar mem- 

 brane are seen fine muscular fibres, which run from the edges of 

 the aperture in a parallel direction with the outer edge of the 

 alar membrane, partly towards the body, partly towards the 

 thumb. The interior surface of the bag is without folds or 

 wrinkles. 



On comparing the descriptions of the corresponding organ of 

 Saccopteryx with the above-described glandular apparatus of the 

 Emballonura canina, several material differences may be disco- 

 vered : first, the bag of the Saccopteryx is somewhat differently 

 situated, viz. just at the bending of the joint of the elbow, while 

 in the Emballonura canina, as has already been mentioned, it is 

 placed near the edge of the wing ; further, the interior surface of 

 the bag in the former is provided with several sharp folds or 

 wrinkles immediately within the opening, which I have not found 

 on the latter ; finally, the bag of the Saccopteryx is much larger, 

 and has the appearance of a sharply limited protuberance on the 

 lower side of the wing, while in the Emballonura canina it is but 

 slightly perceptible. 



The males only of the Emballonura canina possess the above- 

 described organ ; in the females the bag-like cavity is totally 

 wanting, but the lip-formed edges of the fissure exist in a rudi- 

 mentary condition, being represented by two very fine and sharply 

 limited folds of the skin, of which the largest (which corresponds 

 to the inner lip) scarcely rises the eighth part of a line*. This 

 glandular apparatus is no doubt one of the means by which the 

 sexes are enabled to recognise each other ; and it appears to me 

 very probable, that in the Saccopteryx likewise, the bag will 

 prove to be a sexual character, a supposition which may find some 

 confirmation in the fact of the specimen described by Dr. Krauss 

 being a male, and the same, if I am not mistaken, being the case 

 with a specimen in the British Museum, which Mr. Gray kindly 



• This rudimental state is, no doubt, the reason why it has not been ob- 

 served by the Prince of Neu-Wied, who founded his description of this bat 

 upon a single fen\ale specimen. 



25* 



