Bibliographical Notices. 103 



— the Tarantula taking no notice whatever of the instrument, while 

 the Epeira responds readilj^ to it — Dr. McCook says that the diflfer- 

 ence is certainly to be explained by the fact that the fork agitates the 

 strands of the web of Ihe Epeira, and that the sjiider thereby ascer- 

 tains its proximity by the sense of touch ; he then proceeds (p. 304) : 

 " It would indeed be a remarkable fact were it to be established that 

 those spiders which, like the Lycosids, are dependent upon keenness 

 of the senses for their success in capturing prej^ should prove to be 

 destitute of the valuable sense of hearing ; while the web-making 

 spiders, who are so little dependent upon the sense of hearing, and 

 are enabled to accomplish the most important functions of life by 

 the sense of touch alone, should be found to possess hearing in a 

 degree of acuteness. It is not often that one finds a contradiction 

 like this in natural history, viz. that those animals that most need 

 a certain organism or sense have none, while those which are in 

 least need are highly sensitive." But if, as Dr. McCook maintains, 

 the Epeira only perceives the vibration of the fork by means of the 

 vibration of its web, how comes it that, at all events in some cases, 

 it undoubtedly knows the direction of the sound? AVe have seen 

 Mr. C. V. Boys hold a tuning-fork over the back of a large specimen 

 of Epeira cUademata ; but instead of feeling at the strands of the 

 web, as she surely would have done if her only means of ascertaining 

 the proximity of the fork lay in the vibration of these strands, she 

 struck viciously at the instrument in the air with her fore legs, thus 

 showing beyond a doubt that she knew whence the sound proceeded. 

 This fact, it seems to us, proves unquestionably that the Epeira 

 heard the sound, probably by the responsive agitation of some hair 

 or hairs on the body or limbs ; for it is almost inconceivable that the 

 spider's sense of touch can be sufficiently keen to inform her, in a 

 case like this, of the position of the agitating agent. If this be so, 

 we have to face and account for what Dr. McCook considers a 

 " contradiction in natural history." For, whether remarkable or 

 not, the simple fact will remain that, so far as we can judge by 

 their actions, the Epeira has an auditory sense and a Li/cosa has it 

 not. But when criticised, this so-called contradiction merely 

 amounts to an assumption, wbich after all may be but a fiction of 

 the imagination. In the first place it must be remembered that 

 a terrestrial species like a Lycosa must prey for the most part upon 

 insects which, ground-lovers like itself, make little or no sound, or 

 at least can only be heard when on the wing and out of the spider's 

 reach. Therefore an auditory sense would not apparently be of the 

 service to it that Dr. McCook makes out. On the other hand, an 

 Epeira feeds almost whoU}' upon insects which are intercepted by 

 its snare when buzzing on the wing. Consequently it is easily 

 conceivable that some benefit is derived from the possession of a 

 sense which would warn its owner of the approach of prey. But in 

 the second place, it must also be remembered that the capture of 

 prey is not the only necessary in life which might make the exist- 

 ence of an auditory sense beneficial. Avoidance of enemies is at 

 least as important. Now in the chapter devoted to enemies and 



