Miscellaneous. 71 



The sense of sight is imperfect in spiders because all accommoda- 

 tion seems to be deficient. At a short distance Attus arcuatus, Bl., 

 regards a ball of paper borne on a fine wire, or in fact anything 

 that moves, as a fly. At a distance of about 1-2 centim., on the 

 contrary, it is quite able to distinguish a fly from a bee of the same 

 size. The geometrical spiders, in consequence of this short- 

 sightedness, are almost exclusively dependent on the sense of touch, 

 which certainly is developed in an astonishing manner. 



Meta si'gmentata, BL, Zilla x-notata, &c, not onby feel that an 

 object has got into their net, but they can even feel upon which 

 radius it is, when they pull upon this radius from the centre. If 

 they have captured a fly, and a second gets into the net at the 

 moment, the)' must go to the central point or to the radius to which 

 tbe new fly is suspended in order to find it, even though it may bo 

 in their immediate vicinity. 



The senses of smell and hearing are also well developed. I have 

 to add to my previous statements * that Epeira patagiata, Bl., for 

 example, can even distinguish different odours. Thus the smell of oil 

 of turpentine is much more disagreeable to it than that of ammonia. 



Among instinctive proceedings I have especially observed the 

 manufacture of the geometrical web more particularly. First the 

 outer framework is spun ; then, alternately from different sides, the 

 rays, and simultaneously with these the round shelter in the middle ; 

 then a spiral extending nearly to the outer margin, which gives tho 

 whole firmness, and serves as a bridge during the further work ; 

 and finally a spiral thread, set with little drops, from the outer 

 framework nearly to the middle shelter. During the making of tho 

 last-mentioned portion the dry spiral is for the most part destroyed. 

 Some geometrical spiders, as is well known, complete their web and 

 then lie in wait for prey upon the central shelter, sitting with the 

 head downwards. (The webs are more or less vertical, because 

 otherwise an insect would too easily drop out of them.) Others 

 keep, at least in the daytime, in a dwelling placed near the web, 

 connected by a signal-thread with the central shelter of the web ; 

 and others leave one sector unwoven for the signal-thread. Among 

 the latter is Zilla x-notata, BL, which I particularly made use of 

 for my observations. It is remarkable that the first web that a 

 young spider of this species prepares is always perfectly geometrical, 

 and that its dwelling-place at first is the central shelter. The 

 second web in rare instances already shows the defective sector. 

 Generally, however, this form first appears after the preparation 

 of several complete geometrical webs, although, as a rule, before the 

 first change of skin. Sometimes we find as an intermediate step a 

 complete geometrical web with a dwelling beside it. The transi- 

 tion to the second form is, however, very rarely quite smooth. It 

 can, however, by no means be dependent upon external conditions 

 or upon changes of the organs. We have before us here, therefore, 



* Zool. Anz. 1883, p. 207, and Arch, f.micr. Anat. Bd. xxiv. p. 1 (Ann. 

 Mag. Nat. Hist. Nov. 1884, p. 329). 



