202 Kew : Snares or Snap-nets of Triangle Spiders. 



fastened. Thus would be produced the line AC ; and the 

 original line, having" been drawn upward by pulling upon AC, 

 would assume the curved form of AB. The two marginal radii 

 would now be in position. In the next place, presumably, the 

 spider would drop from the point C to B, carrying with her 

 a thread, which, attached at B, would become the base-line of 

 the triangle CABC. Proceeding along BA, carrying with her 

 a thread as before, she may now make another attachment at 

 E, returning upon her course to B, and thence upward on the 

 base-line to E, where the carried thread would be pulled taut 

 and fastened, and would form the third radius EE ; finally, it is 

 supposed, the fourth radius DD would be put into position in 

 a similar way. It is curious to note that while McCook here 

 assumes the lower marginal radius to be part of the original 

 line, Thorell, Sordelli, and Wilder, writing independently, each 

 suppose the upper marginal radius to have this character. 

 Sordelli appears to be the only author other than McCook who 

 has entered into detail as to the order of construction of these 

 lines. His remarks, relating to Hyptiotes paradoxus, already 

 quoted, antedate those of McCook by seventeen years, but the 

 latter author does not appear to have been acquainted with 

 them ; and it is interesting in this circumstance to find that, 

 with the exception just alluded to, the statements of Sordelli 

 and the suggestions of McCook are practically identical. 

 According to the European author, the line AC (in Fig. 3) is the 

 first, AB the second, CB the third, and DD and EE the fourth 

 or fifth respectively. It is quite likely that this author, having 

 ample opportunities for observation, saw the spider spin the 

 lines in the order thus indicated ; but the writer is not clear on 

 this point. 



Wilder, fortunately, twice witnessed the construction of cer- 

 tain of the cross-lines. In 1870 he saw the last cross-line (that 

 nearest the apex) finished ; and, in 1873, he watched the forma- 

 tion " of the last five of these lines. At the time of the latter 

 observation the spider had completed the warp and the first 

 four cross-lines (in the wide basal region of the snare). As the 

 observer took up his position, the creature was passing along 

 the upper marginal radius from the direction of the apex ; 

 reaching the cross-line last completed, she turned round, 

 seemed to make rough measurements with her body, and then, 

 by drawing her spinnerets along the radius for a short distance 

 (about 2 mm.) formed thereon an extended attachment. The 

 spider then allowed her abdomen to fall away from the radius ; 



Naturalist, 



