Title: The descent of man, and selection in relation to sex
Identifier: descentofmansele1874darw (find matches)
Year: 1874 (1870s)
Authors: Darwin, Charles, 1809-1882
Subjects: Evolution; Natural selection; Heredity; Human beings; Sexual selection in animals; Sexual dimorphism (Animals); Sex differences
Publisher: New York : A. L. Burt
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

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nt THE DESCENT OF MAJST. Mr. B. D. Walsh* has remarked, how many different; organs are worked in by nature for the seemingly insignifi cant object of enabling the male to grasp the female^ firmly/' The mandibles or jaws are sometimes used for this purpose; thus the male Corydalis cornutus (a neu- ropterous insect in some degree allied to the dragon flies, etc.) has immense curved jaws, many times longer than those of the female; and they are smooth instead of being toothed, so that he is thus enabled to seize her without injury, f One of the stag-beetles of North America (Liicanus elaphus) uses his jaws, which are much larger than those of the female, for the same purpose but probably Itkewise for fighting, in one of the sand- wasps (AmmopMla) the jaws in the two sexes are closely alike, but are used for widely different purposes; the males, as Prol Westwood observes, areexceed* ingly ardent, seizing their part- ners round the neck with their sickle-shaped jaws;J while the females use 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 hair; and in many genera of water beetles they are armed with a their development. That this can hardly be the case, we may infer from the many recorded cases (see, for instance, Bronn, Geschichte der Natur," B. ii, 1843, s. 164; and Westwood, Transact. Ent. Soc," vol. iii, 1842, p. 195) of distinct species having been observed in union. Mr. MacLachlan informs me (vide " Stett. Ent. Zeitung," 1867, s. 155) that when several species of Phryganidse, which present strongly pronounced differences of this kind, were confined togethei by Dr. Aug. Meyer, they coupled, and one pair produced fertile ova. *The Practical Entomologist," Phila., vol. ii. May, 1867, p. 88. fMr. Walsh, ibid, p. 107. i" Modern Classification of Insects," vol. ii, 1840, pp. 205,206. Mr. Walsh, who called my attention to the double use of the jaws, says that he has repeatedly observed this fact.
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Fi^. 9. Crabro cribrarius. Upper figure male; lower figure female.

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