. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings -- Origin. these organs for burrowing in sand-banks and making their nests. The tarsi of the front-legs are dilated in many male beetles, or are furnished with broad cushions of hairs; and in many genera of water-beetles they are armed with a round flat sucker, so that the male may adhere to the slippery body of the female. It is a much more unusual cir- cumstance that the females of some water-beetles (Dytiscus) have their elytra
. The descent of man, and selection in relation to sex. Evolution (Biology); Sexual selection in animals; Sexual dimorphism (Animals); Sex differences; Human beings -- Origin. these organs for burrowing in sand-banks and making their nests. The tarsi of the front-legs are dilated in many male beetles, or are furnished with broad cushions of hairs; and in many genera of water-beetles they are armed with a round flat sucker, so that the male may adhere to the slippery body of the female. It is a much more unusual cir- cumstance that the females of some water-beetles (Dytiscus) have their elytra deeply grooved, and in Acilius sul- catus thickly set with hairs, as an aid to the male. The females of some other water- beetles (Hydroporus) have their elytra punctured for the same In the male of Crabro cribrarius (fig. 8), it is the tibia which is dilated into a broad horny plate, with mi- nute membraneous dots, giv- ing to it a singular appearance like that of a In the male of Penthe (a genus of beetles) a few of the middle joints of the antennas are dilated and furnished on the inferior surface with cushions of hair, exactly like those on the tarsi of the Carabidae, ' 6 We have here a curious and inexplicable case of dimorphism, for some of the females of four European species of Dytiscus, and of certain species of Hydroporus, have their elytra smooth ; and no intermediate gradations between sulcated or punctured and quite smooth elytra have been observed. See Dr. n. Schaum, as quoted in the ' Zoologist,' vol. 1847-48, p. 1896. Also Kirby and Spence, 'Introduction to En- tomology,' vol. iii. 1826, p. 305. 7 Westwood, ' Modern Class.' vol. ii. p. 193. The following statement. Fig. 8.—Crabro cribrarius. Upper figure, ma e ; lower figure, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectevoluti, bookyear1872
