. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings -- Origin. Chap. X.] COLEOPTERA. 369 -.*. a Trox sabidosus, a gamekeeper who stood by thought that he had caught a mouse; but I failed to discover the proper organs in this beetle. In Geotrupes and Typhseus a nar- now ridge runs obliquely across (r, fig. 25) the coxa of each hind-leg, having in G. stercorarlus eighty-four ribs, which are scraped by a specially projecting part of one of the abdominal segments. In the nearly-allied C
. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings -- Origin. Chap. X.] COLEOPTERA. 369 -.*. a Trox sabidosus, a gamekeeper who stood by thought that he had caught a mouse; but I failed to discover the proper organs in this beetle. In Geotrupes and Typhseus a nar- now ridge runs obliquely across (r, fig. 25) the coxa of each hind-leg, having in G. stercorarlus eighty-four ribs, which are scraped by a specially projecting part of one of the abdominal segments. In the nearly-allied Coprls lunaris, an exces- sively narrow fine rasp runs along the sutu- ral margin of the elytra, with another short rasp near the basal outer margin ; but in some other Coprini the rasp is seated, ac- cording to Leconte,73 on the dorsal surface of the abdomen. In Oryctes it is seated on the pro-pygidium, and in some other Dy- nastini, according to the same entomolo- gist, on the under surface of the elytra. g Lastly, Westring states that in Omaloplia Fig. 25.—Hind-leg , , , , , of Geotrupes ster- orunnea the rasp is placed on the pro- corarius (from sternum, and the scraper on the meta- . r. Rasp. c. Coxa. sternum, the parts thus occupying the /., under surface of the body, instead of the upper surface as in the Longicorns. We thus see that the stridulating organs in the differ- ent coleopterous families are wonderfully diversified in position, but not much in structure. Within the same family some species are provided with these organs, and some are quite destitute of them. This diversity is intelli- gible, if we suppose that originally various species made a shuffling or hissing noise by the rubbing together of the hard and rough parts of their bodies which were in con- tact ; and that, from the noise thus produced being in some way useful, the rough surfaces were gradually de- 73 I am indebted to Mr. Walsh, of Illinois, for having sent me extracts from Leeonte'
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