376 ARACHNIDA ARANEAE CHAP. 



egg-bag, which, since its construction, has been so situated as to 

 be out of the view of the spider. Peckham found that spiders 

 of the genus Theridion, accustomed to the sight of their 

 cocoons, readily recognised them by that sense when removed 

 to a distance. 



The most keen-sighted of the spider tribe are undoubtedly the 

 Attidae, or Leaping-spiders. The little black and white striped 

 Wall-spider, Salticus scenicus, is probably a familiar object to most 

 of our readers, and a very little observation of its movements, like 

 those of a cat stalking a bird, will convince the observer that its 

 visual powers are wonderfully keen and accurate. Its attitude of 

 " attention " on sighting its prey, its stealthy manoeuvring to 

 approach it unobserved, and the unerring certainty of its final 

 leap, are very interesting to witness. 



It is somewhat noticeable that both in the Epeiridae and in 

 the Attidae the two portions of the body, cephalothorax and 

 abdomen, have more than the usual freedom of independent 

 motion. In the Orb-weavers this gives play to the spinnerets in 

 binding up a captured insect, but in the Leaping-spiders it allows 

 of the rapid directing of the large anterior eyes towards the 

 quarry, as it continually alters its position. 



Professor and Mrs. Peckham of Wisconsin l performed some 

 interesting experiments to ascertain the sensitiveness of the 

 spider's eye to colour. Freely communicating compartments of 

 differently coloured glass were constructed, and spiders were con- 

 fined in them, when it was found that red was the most and blue 

 the least attractive hue. This agrees well with what Lubbock 

 found to be the case with ants, but those insects displayed a greater 

 antipathy for blue and not so marked a preference for red. 



HEARING. Most of our knowledge about the auditory sense 

 of spiders is due to experiments performed by C. V. Boys, 2 and 

 repeated by Professor and Mrs. Peckham. 



The spider usually responds to the stimulus in one of two 

 ways ; it either raises its front legs, extending them in ' the direc- 

 tion of the sound, or it allows itself to drop suddenly, as though 

 in alarm. It was only in the case of the Epeiridae that any 

 results were obtained, and these spiders were more sensitive to 

 low than to high notes. Now, as M'Cook points out, it is 



1 J. Morph. (Boston, U.S.A.) i., 1887, p. 403. 

 2 Nature, xxiii., 1880, p. 149. 



