THE SENSES AND THEIR ORGANS. 



297 



time when, having deposited the eggs wiiliiii llie little circular i)atch, 

 she rolls the cover around them into a ball, and then attaches the hall 

 to her spinnerets. This is undoubtedly the univer.sal method with spiders 

 that carry about their egg sacs. The cocoon covering is first sjiun upon 

 some surface, the eggs enclosed, the ball ju'epared, and the last act is attach- 

 ing it to tlie spinnerets. 



Of course, during this process, a spitler whose eyesight is so good that 

 it can perceive its prey at a distance of several inches, must of necessity 

 have seen its cocoon. It would be impossible for us to reach any other 

 conclusion. The confusion in maternal recognition and selection of her 

 offspring cannot, therefore, be accounted for by defective sight. 



Among the Theridioid spiders is a large group of species which Black- 

 wall has placed under the genus Walckenaera, which present some re- 



markable peculiarities in the location of the eyes. These are 

 Turrets clistributed on the anterior part of the cephalothorax, which 



sometimes in females and usually in males is remarkably ele- 

 vated. The drawings here presented (Figs. 289-293) are taken from Black- 

 wall's descriptions of 



Walckenaera acumina- 

 ta, ^ and represent one 

 of the most remarkaljle 

 of these turret like de- 

 velopments of the ca- 

 put for the receptioh of 

 eyes.-^ The length of 

 the female (Fig. 292) 

 is about one-seventh 

 of an incli. The sexes 

 are similar in color, but 

 the male (Fig. 289) is 

 smaller than the fe- 

 male, and the anterior 

 prominence of its ceph- 

 alothorax is much more 

 elongated and slender, 

 measuring about one- 

 twentieth of an inch in 

 length. This eye tur- 

 ret is elevated vertical- 

 ly and dilated near the middle and at the apex (see Figs. 290, 291), the 

 latter dilatation being separated by a transverse groove into a superior and 

 inferior segment, both of which are rougli, with short, strong hairs. On 



' Spiders Gt. Br. & Ir., pi. xx., Fig. 203. 



- See also Mr. E. Simon's Arachnides do France, Vol. V., part III., page S20. 



Walckenaera acuminata. 



Fig. 289. Male. Fig. 290. Eye turret of male, greatly enlarged ; front 

 view. Fig. 291. The same, side view. Fig. 292. Female. Fig. 293. 

 Same, side view of cephalothorax, with outline showing natural size. 

 lAfter Blackwall.) 



