298 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



these enlargements the eyes are seated. Both sexes of this curiously con- 

 structed spider were taken in England in October under stones and on rails. 1 

 It is to be observed that the greatest prominence of the eye turret of 

 Acuminata belongs to the male, and this appears to be the rule with simi- 

 larly constructed species. What can be the cause or the use of 

 this? One would think that such a remarkable development 

 Turrets mug t be intended to serve the spider some special advantage in 

 making its way around its natural site. But until we know 

 something more in detail of the habits of the species we can only venture 

 a suggestion. The probability is that, all these small Theridioid spiders, 

 like many of the minute species dwelling in the United States, spend their 

 life upon or near the surface of the earth, where they weave their loose 

 webs of lines around the bases and among the roots of grasses. It may 

 be taken for granted that the male, in his amorous search after the female 

 during the period of courtship, would find such an eye turret advantageous 

 in detecting the home web and person of his mate amidst such an entang- 

 ling environment. At least, no other advantage can be suggested for this 

 strange exaggeration of the tubercles on the eye space. 



A difficulty which at once arises, is the fact that so many other spe- 

 cies having like habits and location show no peculiarity of a like kind, 

 and appear to have no need therefor. Great numbers of species have 

 eyes placed upon tubercles or slightly elevated parts of the caput, usually 

 of a rectangular or quadrangular shape. In some Epeiroids these tubercles 

 are quite pronounced, and many of the genera are sharply distinguished 

 thereby. In many more genera, and indeed it may be said in 

 , ye , T almost all, the eye or ocellus proper is quite commonly raised 

 and Rows u P on or within a little cup of black chitinous formation, which 

 thus slightly elevates it above the surface of the face. As far 

 as I know, there are not many eyes that appear to be set immediately into 

 the eye space without this enclosing cup. 



Among Saltigrades and Citigrades one pair of eyes is commonly placed 

 at considerable distance behind the others, giving in this way an addi- 

 tional advantage to the species by the seeming ability to observe, to some 

 extent, objects lying behind it. The breaking up of the eyes into rows, 

 generally two, but sometimes three, may serve the same useful purpose. 

 This whole subject is an interesting one, but the facts in my possession 

 are so few that I can do little more than open it for the consideration of 

 future students. 



VI. 



In considering the sense of smell in spiders two questions require at- 

 tention. In the first place do spiders possess this sense at all, and, if so, 



1 Blackwall, idem., page 290. 



