MIMICRY IN SPIDERS. 3G7 



this bunching habit spiders, Orbweavers at least, follow the influence of 

 habit, for when at rest within tlieir nests they almost invariably draw 

 themselves up in the manner described. However, the position is contrary 

 to that generally assumed by spiders making vertical orbs when hanging 

 in wait for prey upon the orb. Then the legs arc stretched backward and 

 forward, not, indeed, in a straight line like Tetragnatlia and Uloborus, but 

 somewhat in tlie jiosition of a St. Andrew's cross or the letter "x," as 

 heretofore described. 



IV. 



Color mimicry in spiders is supposed, first, to facilitate taking prey, thus 



promoting the life of the species, and, second, to protect the mimic from 



assaults of enemies, who are deceived bj' the close resemblance 



-,. . either to surrounding obiects or to some animal obnoxious to 



Mimicry. ... 



the assailant. An interesting example of color mimicry is the 



common spider Misumena vatia. This spider is generally yellow, mottled 

 upon the abdomen, and with darker rings on the legs. It will often 

 be found spread out upon the yellow heart of an ox-eyed daisy, or in like 

 position upon Coreopsis (Plate III., Fig. 1) or golden rod. Here it re- 

 mains and preys on insects frequenting the plant. It certainly closely re- 

 sembles the flower upon which it is ambushed, and the ordinary observer 

 might well fail to notice its presence. On one occasion I found this spe- 

 cies concealed underneath one of the outer petals. of a half opened rose, 

 and, curiou.sly, it had its prevailing 3'ellow greatly modified by a pinkisli 

 cast of color, more closely resembling the rose upon which it was lodged. 

 (Plate III., Fig. 2.) 



Mrs. Treat gives an account of a Laterigrade that appears to be Misu- 

 mena vatia, whose lurking place was in the heart of roses, and was so 

 nearly the same shade of color as the floWer as to make it dif- 

 ^. ' ficult to see her. When the rose began to wither she took up 

 position on a fresh one. The spider was first observed in July, 

 and remained on the same bush about tliree weeks, and then moved to a 

 bright red tea rose, whose stamens were more conspicuous and numerous 

 than the other, and which was visited by a greater number of insects. 

 Misumena went to the centre of one of the flowers, but the stamens were 

 of a deeper yellow than her body, and the surrounding petals made her 

 easy to be seen. She seemed to know this as well as the looker on, and, 

 although more game visited these roses, she did not stay long. The ob- 

 server thought the spider conscious that her safety depended upon the re- 

 semblance, and therefore returned to her old home among the petals of 

 the light colored rose. 



She made no web to entrap prey, but depended wholly upon strategy 

 and muscular strengtli. When waiting for prey she cuddled down in the 

 centre of the flower, and erected her long fore legs in such position that 



