364 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



be likely to deceive these inveterate spider enemies would undoubtedly be 

 a protection to spiders of all tribes. 



But then, with such a theory in mind, we are met at once by the fact 

 that those spiders which are most frequently found within the clay cells 

 of mud dauber wasps, and those which these insects most frequently col- 

 lect as food for their larvae, are the Sedentary groups such as Orbweavers 

 and Lineweavers. They do indeed take the Thomisoi'ds, especially those 

 that lurk on flowers in pursuit of prey, and which, in turn, sometimes 

 capture the wasps. The Saltigrades are also taken; but if I may judge 

 from my own observations, they are least numerously represented of all 

 the tribes except perhaps the Lycosids and the Tunnelweavers. This seem- 

 ing immunity is evidently not due to any likeness of Attidse in general 

 features to wasps, but simply to their manner of life, which, in large meas- 

 ure, screens them from assault, and enables them to escape. Now, the 

 question must rise in considering such a theory, why does not natural 

 selection operate for the protection of those spiders which obviously need 

 protection the most ? 



Is it not remarkable that during all the ages in which the forms of 

 Orbweavers have remained substantially unchanged, as well as the forms 

 of wasps, and during which period the habits of both creatures must have 

 been the same, Nature has refused to work in the direction of protecting 

 the exposed Orbweavers by providing them some analogical resemblance 

 such as that which we remark in the case of Simonella americana ? It 

 seems to me illogical to expect a general law to account for the origin of 

 certain peculiarities in Nature, and yet to exclude this general law or force 

 from operation within the whole field of life with the exception of one 

 very small section. It seems further illogical to hold that this general 

 law would have failed to operate not only in the cases where it seems to 

 be most necessary, but in those wherein all the circumstances are best ar- 

 ranged for its most effective operation. 



While spiders thus abundantly prey upon ants, sometimes the condi- 

 tions are reversed, for when the opportunity presents, the ants will feed 

 upon spiders. In certain cases this takes the shape of a system- 

 o^f ' & tic raiding of the whole section, as, for example, according to 

 Mr. Cambridge, the large red ant of the woods, Formica rufa, 

 destroys spiders so completely, that in localities thickly inhabited by those 

 insects, he had generally found it almost useless to search for spiders. 1 



Whether or not any ant like species are found among Sedentary tribes 

 I do not know. But it entirely passes my imagination to conceive what 

 possible advantage could accrue to an Orbweaver, for example, from resem- 

 blance to an ant. Orbweavers, and yet more frequently Lineweavers, prey 

 upon ants ; but it is not necessary that there should be any resemblance to 



1 Spiders of Dorset, Vol. I., page xxxi. 



