Ciiap. IX. 
SPIDERS AND MYRIAPODA. 
339 
acquired greater size and strength. Mr. Blackwall has 
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 
Greer saw a male that “ in the midst of his preparatory 
46 caresses was seized by the object of his attractions, 
“ enveloped by her in a web and then devoured, a 
“ sight which, as he adds, filled him with horror and 
“ indignation.” 15 
Westring has made the interesting discovery that 
the males of several species of Theridion 16 have the 
power of making a stridulating 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, 4 Introduction to Entomology/ vol. i. 1818, 
p. 280. 
16 Theridion (Asagena, Sund.) serratipes, 4-punctatmn et guttatum ; 
see Westring, in Kroyer, 4 Naturhist. Tidskrift,’ vol. iv. 1842-1843, 
p. 349 ; and vol. ii. 1846-1849, p. 342. See, also, for other species, 
4 Aranese Svecicse/ p. 184. 
z 2 
