[28]

Sept. 14 1868 Necrophorus humator - Rasp on dorsal surface, see Landois - 2 straight parallel, each developed & neat. In ♂ 60/7000 wide in ♀ 44-46/7000 wide. Each plate ridge in both sexes. Equally remote from each other viz about 5/7000 - The whole 2 rasps of ♀ more transparent. But greater difference is in prominence of rasps viz (as measured by forced distance) as about 5 to 2. The rasps of female, are measured from external edges and equally distinct as in male, but as they are narrower the longitudinal space between them is wider in female than in male in proportion of 17 to 15.

(Musical instruments being absent & present in allied genera agree excellently with view that they are sexual characters.)

(There is no difference in underside of elytra of sexes.)

(Dermestes murinus. F. discovered certainly squeals but he cd not discover the apparatus.)

 

[28v]

(Necrophorus Humator)

♀ (old) at base 11 - at top 9

♀ base 10 - top 7-8

♀ base 11-12 - top 7-8

♂ base 9-10 - top 9-10

♂ base 9 - top 7-8

♂ (old) base 11 - top 7

3 males & 3 females measured (Oct 13 68) (including 2 old specimens before measured) The divisions of micrometer have no particular length; but it is clear that distance from summit to summit of rasps, at top & base, are variable, & do not especially differ in the 2 sexes.

 

[29]

Sept 21/68. Cerambyx muschatus rasp on thorax - plates especially fine & close, music very high, of sexes distinguished right that rasp of ♀ is most opake, & for 37 to 38 divisions of micrometer broad; whilst that of male was only 31 to 32 broad.)

Can the rasp act as sexual call?

Trox sabulosus. Frank has found very small & short, (longitudinally) fine rasp on penultimate segment of abdomen. – but (as with Wallaces Beetles) I cannot believe squeak loudly with this apparatus: probably I was right, that it uses tibiæ.

[sketch] Thin membrane

The thick part of membrane hollowed out with only a few rasps ridges beneath it, but broader on each side & ending abruptly to right & left - The whole organ is most weak & rudimentary in function.