1/2 



WALTER LOUIS HAHN. 



less on the up and down stroke than when horizontal. The 

 average expanse of the two species of Myotis is ten inches. If 

 we deduct one inch for the contracted wings and assume the 

 wires to be equally spaced, the probable percentage of hits is 82. 

 There is therefore some avoidance even when the ears are stopped. 

 The fact that bats with the meatus plugged were able to 

 equilibrate and alight on objects which they struck would seem 

 to indicate that the disturbance was not a mechanical one, i. c, 

 due to the weight of the plaster or to sensations caused by its 

 pressure on the tympanum or labyrinth, but that it was due 

 wholly to an interference with sensation, and probably to the fail- 

 ure of vibrations to reach the sensoiy cells of the internal ear. 



Table III. 



Avoidance of Wires. 



Pipistrellus subjlavus. 



' Eyes and ears freed. 

 2 Eyes freed. 



