The Descent of Man

and too small for her to catch without great
difficulty."
Westring has made the interesting discovery
that the males of several species of Theridion
(23. Theridion (Asagena, Sund.) serratipes, 4punctatum
et guttatum; see Westring, in Kroyer,
'Naturhist. Tidskrift,' vol. iv. 1842-1843, p.
349; and vol. ii. 1846-1849, p. 342. See, also, for
other species, 'Araneae Suecicae,' p. 184.) have
the power of making a stridulating sound,
whilst the females are 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 can be detected in the females. It deserves
notice that several writers, including the wellknown
arachnologist Walckenaer, have declared
that spiders are attracted by music. (24. Dr.
H.H. van Zouteveen, in his Dutch translation of
this work (vol. i. p. 444), has collected several
cases.) From the analogy of the Orthoptera and