No. 1.] 



SEXUAL SELECTION IN SPIDERS. 



33 



the black male form of Astia viitata there are three long tufts of 

 black hairs on the eye-region, which are absent not only in the 

 female but also in the other male form. 



Leaving the Aitidie, there are several genera described by 

 Menge, Cambridge, Simon, Thorell, Emerton and others that 

 illustrate curious sexual modifications of the upper part of the 

 face. For example, in the genus Argy- 

 rodes, (Fig. 11), of Simon, while the 

 head of the female is often high and 

 somewhat notched in front, in that of 

 the male each of these divisions of the 

 front part of the head gives rise to a 

 horn, covered at the extremities with 

 hairs. The drawing shows the parts 

 in the two sexes. Emerton in New 

 England Therididss, when speaking of 

 the genus Ceratvnella says : " The heads 

 of the males are usually higher than 

 those of the females, and in some ,jfj«-^i^^tnf ™u|ej:'^^^^^^ 

 species are very large and raised into fi|ura! cephSothLSfot'feiS"; 

 humps ;" and of the genus Cornicularia 



he says that "the males have a hump or horn on the front of the 

 head between the eyes, usually ornamented by flat, stiff hairs. 

 In several species there are two horns, the lower one being small 

 and partly concealed by the upper." There are many other 

 genera in this family, with large numbers of species distributed 

 over different parts of the world. Most of these species are 

 small, but close inspection shows a great deal of sexual differ- 

 ence in the head parts and often also in the falces. 



In male spiders the palpi are modified and serve as organs 

 for the conveyance of the sperm cells to the epigynum of the 

 female. Beside this direct use in the reproductive act they 

 often play an important part as ornamental appendages. The 

 female palpi, are, speaking generally, cylindrical, five-jointed 

 outgrowths of the maxillae, covered with hairs and varying 

 somewhat in length and color ; but throughout the order there 



