USES OF SPIDERS' WEBS. 663 



intentionally in the performance of their aeronautic expeditions, it must always be 

 regarded as a fortuitous circumstance." 



The same writer also remarks that the various directions in which these gossamers 

 are known to sail is in no way attributable to the will of the spider, but merely to the 

 currents of air through which the webs float. He also reviews the opposite opinions 

 regarding the production of the first lines of the web. Some writers say that the spider 

 has the power of projecting its threads in any direction which it may choose, while 

 others assert that it has no such power, and that the creature is forced to wait for a 

 current of air which can bear the slender thread on its breath. After noticing the 

 arguments and experiments on both sides of the question, he comes to the conclusion 

 that the spider is indebted to the air and not to its own projectile capabilities. 



Strong and elastic as these webs may be, they have never yet been put to any useful 

 purpose, save to check the bleeding of a cut finger, or to form the cross-wires of an 

 astronomer's telescope. The thread of many species is suitable enough for manufac- 

 ture, but it cannot be supplied in sufficient quantities. Spiders cannot be kept in any 

 number, as they would be always fighting and eating each other ; and they are so vora- 

 cious that they could not be properly furnished with food, flies being difficult to catch 

 in many parts of the year, and in the cold months quite unattainable. As a proof that 

 if the web could only be obtained in sufficient quantity it might be woven into various 

 articles of apparel, there are now in existence several pairs of gloves, stockings, and other 

 fabrics that have been made, though with very great difficulty, from this substance. 



THE odd-looking spider called Arkys lander is seen on the preceding illustration, at 

 fig. E. It is a native of Brazil and the surrounding countries. The cephalothorax of 

 the spider is orange-yellow, with a line drawn transversely over it, and changing to a 

 brilliant red at the point on each side. The round spots on the abdomen are bright 

 yellow ; the hinder feet are covered only with short down, but those in front are fur- 

 nished with strong spines. 



To return to the illustration on page 662, and to our account of the genus 

 Thomisus. 



At figs. B and D are represented the two sexes of Thomisus citreus, for the purpose 

 of showing the great difference in their dimensions and general shape, the female being 

 twice as long as the male, and, as a necessary consequence, very much larger in cubic 

 dimensions. This species is tolerably common, and is usually found on flowers, whether 

 growing in gardens or in the field. 



The female is a light citron-yellow, with some dark streaks on the cephalothorax, 

 and a double row of round dark spots on the upper part of the abdomen. The yellow 

 color extends over all the limbs. The male, on the contrary, is light leafy green, with 

 two black bands running down the abdomen, and a darker streak on each side of the 

 cephalothorax approaching to brown. The first and second pairs of legs are dark 

 chestnut-brown, while the others are green like the body, so that it is a very pretty- 

 colored creature, and so unlike the female that few persons would believe it to belong 

 to the same species. 



ON the next illustration we have more examples of this active family. At figs. A 

 and C are given the two sexes of the same species, in order to show their dissimilarity, 

 a phenomenon very frequent among spiders, and which renders the task of arranging 

 them correctly a matter of no slight difficulty. 



This is a very active spider, and can run swiftly even upon polished substances. It 

 is found in well-wooded districts, and is remarkable for the speed with which it runs. 

 The cocoon made by the female is rather large, being nearly a quarter of an inch in 

 diameter, and containing about seventy pale yellow eggs laid loosely in a white cell. 

 This cocoon is not carried about by the female, but is lodged in a larger cell of dull 

 white silk ; and this cell is generally placed within a leaf, the edges of which are drawn 

 together by stout lines of the same silken fabric. A dead and already withered leaf 

 is chosen for this purpose. 



