196 Kew : Sfiares or Snap-nets of Trici7igle Spiders. 



tion of the snare, accompanied by an illustration (Fig. 1). In 

 the autumn of 1871 he found the spider within the city of Milan, 

 close to the Museum to which he was attached, and was thus 

 able to observe it at leisure. It begins its snare, he says, by 

 extending an inclined thread between two small branches, in 

 such a manner that the lower end is fixed firmly to the free 

 extremity of one of the branches ; and this extremity becomes 

 the pivot of the snare and the point at which the spider remains 

 in observation. From a point upon this thread, more or less 

 near its lower end, the spider sends down another thread, much 

 inclined, towards some lower branch, and placed so as to fall in 

 a vertical plane with the first thread. Then by a- third thread, 

 vertical or almost so, the creature joins the first two, forming 

 thus the triangular outline of the snare. From the angle 

 formed by the first two threads are extended in succession two 

 other threads to the opposite side of the triangle, in such 

 a manner that they belong, as a rule, to the second, not to the 

 first, thread. The warp of the snare, consisting of four con- 

 vergent threads (radii) and a base-line, is now complete. Upon 

 the convergent threads, however, have still to be woven other 

 threads said by this author to be perfectly comparable to the 

 spirals of Epeira, but here reduced to simple segments, instead 

 of embracing a complete circle. These segment-threads (cross- 

 lines) vary in number, from snare to snare, from about 15 to 25. 

 The angle formed by the marginal radii also varies ; as also 

 does the size of the whole structure. The parting of the two 

 intermediate radii from the lower marginal radius, not from the 

 upper, and not both from the same, but from neighbouring 

 points, are circumstances believed by the author to be useful in 

 the matter of transmission of vibrations : he thinks that this 

 disposition is calculated the more effectually to make known to 

 the spider the exact part of the snare in which a struggling 

 insect is to be found. * 



These authors do not, as far as the writer is aware, make 

 any mention of the snapping process, which American observers 

 fully describe. I am indebted to Mr. Cambridge, however, for 

 the information that his nephew, Mr. Fredk. O. Pickard- 

 Cambridge, who was with him when Hyptiotes paradoxus was 

 discovered in the New Forest, observed the habit in this animal 



* F. Sordelli, Intorno alia tela ed ai costumi di una specie di rag-no 

 {Mithras paradoxus), Atti della Societa italiana di Scienze Naturali in 

 Milano, XV. (1872), pp. 22-30. 



Naturalist, 



