446 TRANSACTIONS OF THE LINNiEAN SOCIETY. 



first tarsal joint of the hind leg are two parallel rows of spines, 

 moveable at the* pleasure of the animal : the spines in the 

 upper row are considerably curved, and taper to a point ; those 

 of the lower row are stronger, more closely set, and less 

 curved; the spider presses its spinners against one of the 

 glossy lines, which are the main-stays of its snare, and, 

 emitting from them a small quantity of liquid gum, attaches 

 to it several fine threads ; the foot of one of the hind-legs is 

 then applied to the upper part of the first tarsal joint of the 

 other hind-leg, and the apparatus of spines is thus brought 

 immediately beneath the spinners, at a right angle with the 

 line of the abdomen ; the apparatus of spines, by a slight 

 motion of the leg, is forced backwards across the mammulcsj 

 the diverging extremities of which it touches in its transit ; the 

 operation is rapidly repeated, and the lines of the flocctdus 

 are produced, the spider making room for them by raising and 

 advancing its abdomen. Mr. Blackwall remarks that Mygale 

 avicularia, Drassus melanogaster, and Salticus scenicus, 

 have only two claws on each foot, and Epeira apoclisa eight. 

 Naturalists have generally supposed spiders invariably to have 

 but three. He further observes, that the nets of geometri- 

 cians are composed of three different kinds of silk ; and that 

 although nets lose their viscidity when exposed to the influence 

 of sun and weather, yet, when artificially protected from the 

 effects of these, they retain it almost unimpaired for many 

 months. With regard to the ecdysis of spiders, Mr. Black- 

 wall observes, that the thorax opens laterally, disuniting imme- 

 diately above the insertion of the mandibles and legs, not 

 from the centre, as Dr. Leach implies ; this line of separation 

 extends to the abdomen, which is next disengaged, the extri- 

 cation of the legs being the last and most difficult operation, 

 though facilitated, as Mr. Blackwall supposes, by. the spines 

 with which they are furnished : when the spider is quite free 

 from the slough, it remains for a short period in a state of 

 great exhaustion, suspended by a thread from the spinners, 

 connected with the interior part of the cast skin ; after being 

 perfectly quiescent for some time, in order that the new skin 

 may dry and consolidate in some degree, as well as, probably, 

 for the sake of repose, it attaches itself to the suspensory line 

 by its feet, and, climbing up, it returns to its retreat. 



Page 487. — Remarks on the PulvilU of Insects, by John 



