The Descent of Man

indebted to Mr. E.W. Janson, for information
and specimens. I may add that my son, Mr. F.
Darwin, finds that Dermestes murinus stridulates,
but he searched in vain for the apparatus.
Scolytus has lately been described by Dr.
Chapman as a stridulator, in the 'Entomologist's
Monthly Magazine,' vol. vi. p. 130.), the
rasp is seated on the dorsal apex of the abdomen,
on the pygidium or pro-pygidium, and is
scraped in the same manner by the elytra. In
Heterocerus, which belongs to another family,
the rasps are placed on the sides of the first
abdominal segment, and are scraped by ridges
on the femora. (76. Schiodte, translated, in 'Annals
and Magazine of Natural History,' vol. xx.
1867, p. 37.) In certain Curculionidae and Carabidae
(77. Westring has described (Kroyer, 'Naturhist.
Tidskrift,' B. ii. 1848- 49, p. 334) the stridulating
organs in these two, as well as in other
families. In the Carabidae I have examined
Elaphrus uliginosus and Blethisa multipunctata,
sent to me by Mr. Crotch. In Blethisa the