CHEIROPTERA; THE BATS. 



103 



in the main building, besides several thousand in out-buildings, there were nine thousand six 

 hundred and forty killed. 



Audubon relates an amusing incident which occurred to a guest of his, whom he does not 

 mention by name, but who is known to have been the late M. Rafinesque, an eminent naturalist 

 who made his home in our country. "The latter had been assigned a room, and when it was 

 waxed late, and we had all retired to rest, every person I imagined was in profound slumber, 

 save myself, when of a sudden I heard a great uproar in the naturalist's room. I got up and 

 reached the door, when, to my astonishment, I saw my guest running about the room naked, 

 holding the handle of my favorite violin, the body of which he had battered to pieces against 

 the walls trying to kill the Bats which had entered by the open window ; probably attracted 

 by the insects around his burning candle. I stood amazed, but he continued running around 

 the room until he was fairly exhausted, when he begged me to capture one of the animals, as 

 he felt sure they were a new species." 



The first peculiarity in the Bat form which strikes the eye, is the wide and delicate mem- 

 brane which stretches round the body, and which is used in the place of the wings with which 



SKELETON OF BAT. 



birds are furnished. This membrane, thin and semi-transparent as it is, is double in structure, 

 being a prolongation of the skin of the flanks and other portions of the animal, and, therefore, 

 having its upper and under surface, in the same manner as the body of the creature itself. The 

 two surfaces are so clearly marked that, with ordinary care, they can be separated from each 

 other. Along the sides, this double membrane is rather stronger and thicker, but, as it 

 extends from the body, it assumes greater tenuity, until at the margin it is so exquisitely thin, 

 that the tiny blood-corpuscules, which roll along the minute vessels that supply the wing with 

 nourishment, can be seen clearly through its integument, by the help of a good microscope. 



In order to support this beautiful membrane, to extend it to its requisite width, and to 

 strike the air with it for the purposes of flight, the bones of the fore-part of the body, and 

 especially those of the arms and hands, undergo a singular modification. 



The two bones of the fore-arm are extremely long, and the bone which is scientifically 

 known by the name of the "ulna,'" is extremely small, and in many species almost wholly 

 wanting. The reason for this arrangement is, that the great object of these two bones is, by 

 the mode in which they are jointed to each other, to permit the arm to rotate with that move- 

 ment which is easily shown by the simple process of turning the hand with its palm upwards. 

 This latitude of motion would not only be useless to the Bats, but absolutely injurious, as the 

 wing-membranes would not be able to beat the air with the steady strokes which are needful 

 for maintaining flight. Therefore the arm is rendered incapable of rotation. 



