C;iai\ IX. SPIDERS AND MYEIAPODA. 339 



acquired greater size and strength. Mr. Blackwall Las 

 sometimes seen two or more males on the same web 

 with a single female ; but their courtship is too tedious 

 and prolonged an affair to be easily observed. The male 

 is extremely cautious in making his advances, as the 

 female carries her coyness to a dangerous pitch. De 

 Geer saw a male that " in the midst of his preparatory 

 " caresses was seized by the object of his attentions, 

 " enveloped by her in a web and then devoured, a 

 " sight which, as he adds, filled him with horror and 

 " indignation." 15 



Westrino* has made the interesting discovery that 

 the males of several species of Theridion 16 have the 

 power of making a striclulating sound (like that made 

 by many beetles and other insects, but feebler), whilst 

 the females are quite mute. The apparatus consists of 

 a serrated ridge at the base of the abdomen, against 

 which the hard hinder part of the thorax is rubbed ; 

 and of this structure not a trace could be detected in 

 the females. From the analogy of the Orthoptera and 

 Homoptera, to be described in the next chapter, we 

 may feel almost sure that the stridulation serves, as 

 Westring remarks, either to call or to excite the 

 female ; and this is the first case in the ascending scale 

 of the animal kingdom, known to me, of sounds emitted 

 for this purpose. 



Class, Myriapoda. — In neither of the two orders in 

 this class, including the millipedes and centipedes, 



15 Kirby and Spence, ' Introduction to Entomology,' vol. i. ISIS, 

 p. 280. 



16 Tberidion (Asagena, Sund.) serratipes, 4-punctatum et guttatum ; 

 see Westrir.g, in Kroyer, ' Naturhist. Tidskrift,' vol. iv. 1842-1843, 

 p. 319; and vol. ii. 1846-1849, p. 342. See, also, for other species, 

 ' Aruneui Svecicso,' p. 184. 



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