USES OF SP1DEES' 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 manufacture, 

 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 voracious 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 furnished 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 colour 

 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 cephalo- 

 thorax 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-coloured 

 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. 



