358 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Fig. 316. An Ant 

 spider, Syne- 

 mosyna for- 

 mica Hentz. 



resemblance to liymenopterous insects, is drawn from a specimen sent me 

 by Professor Peckham, and was collected in South America. (Fig. 317.) 

 I do not know the particular genus to which this species be- 

 longs. The number of species having this characteristic form 

 appears to be quite limited in any given locality, particularly 

 of temperate climates ; but there are probably many more 

 than has been supposed, for Professor Peckham informs me 

 that he has at least seventy-iive species in his private col- 

 lection. 



According to Mr. Cambridge, the most striking instance of 

 resemblance among British spiders is that of Micaria scintalans, found in 

 some abundance in the Isle of Portland. This spider so nearl}^ resembles a 

 large ant which abounds in the same locality, that it requires the 

 ^^ ^^ second look of even a practiced eye to be sure whether it be really 

 spider or ant. The advantage, or " protective effect," afforded 

 to one thus resembling another is not always easy to be understood at 

 once. It may often consist in tlie protection from certain dangers to which 

 the creature resembled is either not liable or may be specially guarded 

 against. Thus the ants of Portland, being of a hard and horny nature, 

 may not be a favorite food for those enemies which would find an agree- 

 able morsel in the softer and more succiilent spider. The latter, therefore, 

 would deceive, and so escape such enemies, from its resemblance to the dis- 

 tasteful ants. In other cases (and, possibly, also in the one just mentioned) 

 Cambridge thinks the resemblance may give the resembler a chance of ob- 

 taining its prey more easily. Thus, in the south of Africa there is a spider 

 resembling an ant even more closely than the Portland species. The habit 

 of this ant is to feed on honey dew along with mul- 

 titudes of insects of other orders. These latter have 

 no dread nor suspicion of the ants, which, in fact, 

 have a common object in view, and do the other in- 

 sects no harm. But then, under cover of the close 

 resemblance to the ants, come the spiders, who, un- 

 suspected and unresisted, regale themselves at their 

 leisure upon the defenseless insect. 



Having recorded the facts, it may be well to con- 

 sider some of the theories advanced to account for 

 them. In general, it may be said that this 

 mimicry is considered as protective. Its use 

 is, first, to enable the mimic to more readilj^ 

 obtain necessary food among its natural prey ; or, sec- 

 ond, to protect it from natural enemies, particularly 

 (as in this case of form mimicry) from some enemy that especialty threatens 

 its existence. Darwin applies to these analogical resemblances, or adapt- 

 ive resemblances, as he calls them, his theory of natural selection. He 



Darwin's 

 Theory. 



Fig. 317. An ant like spider 

 from South America. 



