222 



WEB-SPIDERS. 



FEMALE OF DrClSSUS LAYING 

 HER EGGS. 



the mother carries the cocoon about with her, either attached to her spinners or 

 clasped between her jaws. The young hatch inside the cocoon, and subsequently 

 make their way to the outer world through a rupture in its walls. They appear 

 in a helpless state, either clinging together in clusters, as in the Argiopidce ; staying 



in the nest, as in the jumping spiders ; or clambering 

 on to their mother's back, as in the wolf - spiders. 

 During growth the skin is periodically cast, the mem- 

 brane of the cephalothorax splitting above the base of 

 the limbs, and the carapace being raised to make an 

 aperture, through which the body with the new skin 

 emerges. The young spider is then soft, limp, and at 

 the mercy of its enemies, until the integument becomes 

 sufficiently hard and resisting to afford firm support 

 to the muscles. Consequently, during this time, many species seek shelter in 

 silken tubes spun for the purpose. On an average, perhaps, spiders undergo about 

 eight or ten moults before reaching maturity, which is attained during the period 

 intervening between the last moult and the last but one, so that the males and 

 females, which during growth are much alike, emerge from the final casting in a 

 fully developed state. In this stage the two sexes are distinguishable, the female 

 having the palpi normally constructed, while in the male the terminal segment 

 of this appendage carries on its lower surface an organ which in its simplest form 

 is somewhat flask-shaped, but is more 

 often variously modified and compli- 

 cated. The male, also, is generally 

 rather the smaller of the two, some- 

 times indeed, as in many tropical 

 members of the family Argiopidce, 

 being of quite insignificant size in 

 comparison with the female. He also 

 has longer legs and a thinner abdomen, 

 being thus the more graceful and 

 active of the two. In the most 

 sedentary of all spiders, or those 

 belonging to the families Theridiidce 

 and Argiopidce, still more striking 

 differences often occur, the front part 



of the carapace being sometimes raised into a high pinnacle-like outgrowth. When 

 the two sexes are approximately equal in size, the male is comparatively safe from 

 his spouse during the period of courtship, but when, as in the Argiopidce, he is much 

 the weaker of the two, the female often avails herself of her superiority in size and 

 strength to devour her mate. The first uses of the silk-glands seem to be to supply 

 material for the construction of the cocoon, and of a tent or tubular retreat for 

 the protection of the mother and young, or for the latter when passing through 

 the dangers attendant upon the casting of the skin. Such cases are also used for 

 the same purpose by many species during the winter months in temperate latitudes, 

 and during drought in more tropical climes. It thus appears that, in the first 



female of wolf-spider (Pardosa amentata) carrying 



HER COCOON. 



Below is shown the arrangement of the eyes when 

 seen from above. 



