406 PROCEEDINGS OF THE ACADEMY OF [May, 



or moving when the chirping or singing began. If they were moving 

 when the music began they did not cease, but continued to move as if 

 nothing were happening. Eighteen individuals of Lycosa and Phidip- 

 pus were employed. 



Therefore if spiders have any auditory sense why do they not 

 respond to the very sounds which a human being can hear at all times 

 immediately in their neighborhood? If quiescence can be considered 

 as a sign of hearing why did not these spiders stop moving when the 

 crickets began to chirp or when the katydids began to sing? Further- 

 more large spiders can easily catch crickets and small katydids, but 

 as yet there are no observations which show that the sense of hearing 

 aids araneads in capturing their prey. One clay I saw a L. scutulata 

 and a small katydid on the same weed. The insect sang continuously, 

 I watched the spider carefully for several minutes, however it did not 

 show the least sign of hearing the katydid as far as I could observe. 



(c) Function of the Lyrifonn Organs. 



In order to ascertain whether the olfactory organs are localized in 

 the palps or in the maxillre, the former were first removed from eleven 

 specimens of Phidippus. The operation was performed by seizing the 

 coxa of the palps with a small pair of forceps, then by giving a quick 

 jerk the appendage was detached, thus leaving only a very small 

 opening through which a minute drop of blood emerged. To cut the 

 appendages off caused the specimens to lose too much blood which 

 in many cases was fatal. The maxilla 1 of the same eleven were re- 

 moved in the same way the second day after the removal of the palps. 

 These spielers were the only ones found which were able to endure a 

 double operation of this kind, but after such an operation they did 

 not hesitate to catch and eat flies as usual. The following table gives 

 the results of the average time in seconds for the five oils before removal 

 of palps, after removal of palps and after removal of palps and maxillsp 



both. 



Before removal After removal After removal of 



No. of of palps of palps palps and maxillae 



specimen. (in seconds). (in seconds). (in seconds). 



77 3 4 4 



75 7 s 7 



97 5 5 4 



98 3 5 14 



99 4 5 6 



106 4 4 4 



IDS 7 7 7 



123 7 7 7. 



129 3 3 4 



130 6 4 4 



131 4 5 5 



Average *.5.0 5.2 6.0 



