TIIK SKN'SKS AND THKIR ORGANS. 321 



If we suppose that the species of spiders in which the male is provided 

 with stridulating apparatus, possesses -it for utility in courtship, and uses 

 it for love calls, as is generally thought is the case with orthopterous in- 

 sects, then we must also suppose that auditory organs exist, at least in the 

 female spider. In other words, spiders are not deaf; they can hear. It 

 is true that distinct auditory organs have never been found, at least have 

 never been recognized as such, and, if spiders hear, they must hear by 

 means of sense organs widely different from any possessed by animals that 

 have the power of hearing. 



If, further, we suppose that those species wherein stridulating organs are 

 possessed in common by male and female, use them to make mutual calls, 

 like the notes of birds or like the sounds uttered by higher vertebrate an- 

 imals, then we are also to infer the power of hearing in the male as well 

 as in the female. 



This much, at least, appears reasonably certain, that the theory that 

 the organs above described are proper organs of stridulation, whose pur- 

 pose is to produce sounds that will be heard by the opposite sex, is de- 

 pendent upon the demonstration of the fact that spiders possess organs of 

 hearing. If we are able to affirm the presence of auditory organs in spi- 

 ders, we may then conclude that the way at least is open for the theory 

 that stridulating organs are common for mutual communication by sound 

 between the sexes. Until this be established, the theory rests upon a very 

 uncertain foundation. 



Concerning the observations upon the stridulating Mygale described by 

 Mr. Peal, and announced by Professor Wood-Mason, I would remark that 

 I have kept for many years in succession living species of both 

 Mlid males and females of the large Mygalidse. One of these (Eury- 

 pelma hentzii) I had in my possession for a period of nearly six 

 years, and one living at this date has been with me about five years. I 

 have often seen them assume the attitude described by Mr. Peal. When 

 I have tested their appetite for small vertebrates by putting mice into their 

 artificial home, or have given them large insects, as locusts, or when I 

 have teased them with a pencil, or annoyed them in any way, it is their 

 invariable habit to throw themselves into the rampant position which 

 Mr. Peal has described and illustrated. This position I have frequently 

 sketched from various points of view, and from some of these sketches 

 Figs. 303 and 304 have been engraved. But in all these cases I have 

 never heard any other sound than that which I regarded as the clatter- 

 ing of the fangs as they were struck together in the movements of the 

 mandibles under the powerful influence of hunger or fear. No sound that 

 I could at all regard from any other standpoint has it ever been my op- 

 portunity to detect. Such negative evidence, of course, amounts to little 

 amounts to nothing, indeed in the face of positive testimony. I only 

 state it as serving to qualify any conclusions which we may be disposed 



