706 



SPIDER. 



ascends along the radius until she is able to lay hold 

 of the next radius, dawn which she descends until she 

 reaches the spot exactly opposite to where the 

 thread had been attached ; she then quits her hold 

 with the hind legs, and the thread is immediately 

 glued to the proper spot in the next radius. In this 

 manner she proceeds until the whole of the net is 

 completed ; and it is quite an amusing sight to watch 

 one of the small geometric spiders engaged in this 

 construction ; the rapidity with which the cross 

 spiral threads are fixed in their proper places is quite 

 astonishing. 



Another interesting spider is the Clubiona atrox, 

 which builds its web in the corners of windows, the 

 crevices of walls, or in the branches of shrubs growing 

 near buildings. We are indebted to Mr. Blackwall 

 for a very valuable Memoir on the Structure and 

 Economy of Spider?, published in the Linnacau 

 Transaction?, in which a description of this nest is 

 given, from which the following is an extract. " On 

 the objects surrounding the spot selected for its re- 

 treat it extends to a considerable distance, but with- 

 out any apparent regularity of design, a number of 

 fine shining lines intersecting each other at various 

 angles, to which it attaches other lines, or rather fas- 

 ciculi of threads, of a more complicated structure, and 

 of a pale blue tint, nearly approaching the colour of 

 skimmed milk. These compound threads or flocculi, 

 which in exposed situations retain their delicate hue 

 fora short period only (old webs being generally of a 

 dull or sullied white, not at alt advantageous to their 

 appearance), are arranged on the first spun glossy 

 lines, both in longitudinal and transverse directions. 

 When recently produced, they adhere strongly to 

 such insects as come in contact with them, and, though 

 perfectly inelastic, may be drawn out into fibres of 

 extreme tenuity. A communication between the 

 snare of this spider and its retreat, is established by 

 means of a funnel-shaped tube of a slight texture, 

 whose smaller extremity is in immediate contact with 

 the latter, and indeed sometimes constitutes the ani- 

 mal's abode. Not (infrequently two or more tubes 

 occur in the same web, by one or other of which the 

 spider usually effects its retreat when disturbed." 



The same author has noticed the curious fact that 

 those species of spiders, which form geometric nests, 

 are furnished with several claws on each foot, whilst 

 some of the jumping spiders, and some others, have 

 only two claws. In several species of Epeires it will 

 be distinctly perceived that the interior part of their 

 feet is provided with several claws which have a de- 

 gree of curvature, are finely pointed, and are furnished 

 with tooth-like processes in the under side. In Epeira 

 apocHsa there are as many as five of these claws, 

 which, in addition to the three upper claws previously 

 known, give a total of eight to each foot. There is 

 also a strong moveable spine inserted near the termi- 

 nation of the tarsus of each posterior leg on the under 

 side, which curves upwards at its extremity, and which 

 by the action of the flexor muscles is brought in im- 

 mediate opposition to the claws, by means of which 

 the animal is enabled to hold with a firm grasp such 

 lines as it designs to attach itself to ; and hence it is 

 obvious why these spiders usually direct their heads 

 downwards when they occupy the centre of their nets. 



Spiders, in regard to the construction of their webs, 

 may be naturally divided into two great groups, which 

 have been named the sedentary and the wandering 

 spiders, The latter do not construct regular webs, 



but either live a vagabond life, as indicated in the 

 article SALTICUS, or merely throw out a few loose 

 and irregular lines in the neighbourhood of their nest. 

 The sedentary spiders comprise two divisions, those 

 which form nets and those which weave webs. The 

 net-weavers are again divided into the geometric spe- 

 cies, and those which construct webs of an irregular- 

 form, the rneshes being at certain distances apart, but 

 not arranged in concentric circles. This group, which 

 is in general composed of minute spiders, is the most 

 curious on account of the singular and astonishing 

 variety in the operations of the species of which it is 

 composed. The genus Theridion may be mentioned 

 as the typical group. The web-weavers spin a closer 

 material than the former, and, like the net-spinners, 

 are divisible into two groups, the cloth-weavers which 

 suspend their hair or rnat-like webs horizontally be- 

 tween plants without any circular retreat (genus, 

 Linyphia, &c.), whilst the other section may be called 

 tapestry workers, suspending their webs in the angles 

 of walls, &c , furnished with a circular retreat formed 

 like the rest of the web. The domestic spider is an 

 example of this division. 



During the summer and early autumn months, it is 

 not an uncommon circumstance to observe numerous 

 long floating threads in the air, at one end of which a 

 minute spider is found to be attached ; the mode in 

 which this is effected has been the subject of con- 

 siderable discussion. Some authors contend that 

 the spider has the power of directing these threads 

 at pleasure towards a determined object. Others 

 maintain that the thread is discharged indepen- 

 dently of any influence from the atmosphere. Others 

 again, that it is entirely electrical. But the most 

 generally received opinion is, that the spider, directing 

 its spinnerets in the direction of a current of air, dis- 

 charges a thread which, being exceedingly light, is 

 carried on by the air to such a length as to be able, 

 from its buoyancy, to support the slight weight of the 

 spider itself. Thus Gilbert White says, "every day 

 in fine weather in autumn do I see these spiders 

 shooting out their webs, and mounting aloft ; they 

 will go off from the finger if you will take them into 

 your hand," although he adds, " but what I most 

 wondered at was that it went off with considerable 

 velocity in a place where no air was stirring, and I 

 am sure that I did not assist it with my breath." 



Leslie made the same observation on nearly thirty 

 different species of spiders, and found the air filled 

 with young and old, sailing on their threads, and 

 doubtless seizing gnats and other insects in their pas- 

 sage ; there being often manifest signs of slaughter, 

 legs and wings of flies, &c., on these threads, as well 

 as in the webs below. These threads are, however, 

 often found without any attendant spider, and it is 

 not improbable that these are threads which have 

 been in the first instance woven amongst the grass 

 and low herbs, which are sometimes observed to be al- 

 most completely carpeted with these productions, and 

 which, being dried by the sun, and raised by currents 

 of air, are wafted about in the atmosphere, until a 

 perfect cairn brings them to the surface again. In 

 France the floating threads, which support the small 

 spiders, are called fits de la Vierge, and it has been 

 supposed that they were exclusively formed by a 

 spider which has been named Aranea obstetrix ; but 

 this is not correct, neither is the species here noticed 

 anything else than a young and imperfectly described 

 individual belonging to the genus Epeira. 



