144 PROCEEDINGS OF THE ACADEMY OF [Jan., 



legs. Certain Attids, according to the account of the Peckhams, 

 exhibit courtship motions of such a very bizarre nature that they 

 would seem at first sight as not referable to movements shown when 

 the male is not sexually excited; yet some of them may be found to 

 be excessive expressions of some of the latter group of movements. 



Thus the motions of the male in courtship are to be directly ex- 

 plained as a muscular expression of his intense eagerness, of vitality 

 in its highest state; though some, at least, of these motions are merely 

 exaggerated repetitions of movements which he performs under other 

 conditions. Such performances probably do stimulate sexual eager- 

 ness in the female, by advertising the performer as a male; but there 

 is no evidence that the male consciously performs for that end. It is 

 as a man under the influence of strong drink : smiles are produced by 

 his antics, but he does not consciously occasion the smiles. 



The male alone does not make all the approaches, but sometimes 

 the female likewise. Thus in Lycosa scutulata the female taps the 

 male with her legs when she is willing for copulation, and the females 

 of the other Lycosids studied by me bend their heads down to the 

 ground as a similar indication. The female of Theridium tepidariorum 

 signals very energetically to the male, by repeated pulls upon the wel)- 

 lines, and appears to be first in the courtship. Other females, as of 

 the Pholcida and some Epeirida;, give no active expression of readi- 

 ness, but by remaining perfectly quiet, thereby not showing hostility, 

 assure the males of their willingness. The only case I know of when 

 the male seizes the female l^y storm is Tegenaria derhami. Since the 

 male ceases his courtship as soon as the female gives the signal of desire 

 on her part, very plainly a portion of the delay before the copulation 

 is due to the male testing the eagerness of the female. 



Sexual selection may well be, in some cases, the process which has 

 occasioned secondary sexual differences, and in the case of the spiders 

 the view of the Peckhams in this matter is probably correct. That is 

 to say, the differences in the males are due, not to "greater vitality" 

 of the male sex, but to selection by the females. Yet I would make 

 the point that there is no evidence that the females are influenced by 

 any esthetic sense of the beautififl in males — that the females do not 

 select males that seem most beautiful to them; but that they select 

 those males which, by peculiarities in movements, color or form, 

 most quickly and certainly announce their sex. Other things being- 

 equal, the male that is most eager would be most active in his court- 

 ship motions, and would stand the chance of being selected by the ex- 

 pectant female, since he would be advertising his sex most prominently ; 



