2 1 2 Kew : Snares or Snap-nets of Triangle Spiders. 



the fact that the cross-lines of the full-orb of ULoborus are not 

 beaded as in Epeirid-orbs, but flocculent as in Hyptiotes. 



With regard to the snapping- operation — commonly supposed 

 to be peculiar to Hyptiotes — it is true that nothing clearly com- 

 parable is known among ordinary typical orb-weavers. Many 

 of these latter, however, vibrate and even suddenly jerk their 

 snares : according to Blackwall the Epeirids pull with their feet 

 the radii immediately in connection with the part of the snare 

 in which prey is entangled ; and, suddenly letting go their hold, 

 they thus produce a vibratory motion in the snare ; * Wilder 

 has observed that ' ordinary Epeiridce, as well as Nephila, are 

 accustomed to vibrate their snares, when touched by insects;'! 

 and many, perhaps all of them, ' sometimes seize several radii 

 in their claws, and draw them up and let them go suddenly'; t 

 McCook states further that Epeirids, as they move cautiously 

 toward their prey, sometimes pause and give two or three quick 

 jerks ; and those which, sitting in their dens, hold a trap-line in 

 their claws, ' frequently pull upon it, increasing the tension by 

 drawing it towards themselves, and then letting it go again, 

 making a series of rapid jerks.' In these cases, however, as 

 McCook adds, there is no coil of slack and no true snapping of 

 the net. Moreover, the purpose of these movements does not 

 seem to be that of increasing the entanglement of prey ; for, 

 while one can well imagine that such movements may often 

 contribute to the embarrassment of a captured insect, McCook, 

 who appears to have given considerable attention to this point, 

 was never able to observe that such was the case. |j All things 

 considered, however, one cannot resist the conclusion arrived at 

 by Wilder that the habits now mentioned may be the basis of 

 the remarkable method by which Hyptiotes assures the entangle- 

 ment of its prey. § 



* Blackwall, Researches in Zoology, ed. 2, 1873, p. 288. 

 t Wilder, 1873, I.e. 

 % Wilder, 1875, I.e. 



|] McCook, 1889, torn, cit., pp. 195-207, 248-9, 338-9. Blackwall observes 

 that Epeirids seldom fail by these means to excite ensnared insects to 

 action, and guided by the struggles thus brought about, the spider runs 

 along the most contiguous radius to seize the victim ; by these means also 

 the spider probably ascertains, in the first instance, whether the entangled 

 object is animate or inanimate (Blackwall, 1873, I.e.), and according to 

 McCook, she appears also to determine the weight and energy of the 

 victim in the same way. (McCook, 1889, I.e., p. 338.) 



§ Wilder, 1873, I.e. ; 1875, I.e. 



Naturalist, 



