342 
SEXUAL SELECTION. 
Part II. 
organs , 2 “it is astonishing/’ as Mr. B. D. Walsh 3 has 
remarked, “ how many different organs are worked in 
“ by nature, for the seemingly insignificant 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 neuropterous insect 
in some degree allied to the Dragon-flies, &c.) has im- 
mense curved jaws, many times longer than those of the 
female ; and they are smooth instead of being toothed, 
by which means he is enabled to seize her without 
injury . 4 One of the stag-beetles of North America 
( Lucanus elajohus ) uses his jaws, which are much larger 
than those of the female, for the same purpose, but 
probably likewise for fighting. In one of the sand- wasps 
(. Ammojohila ) the jaws in the two sexes are closely 
alike, but are used for widely different purposes ; the 
males, as Professor Westwood observes, “are exceed- 
“ ingly ardent, seizing their partners round the neck 
“ with their sickle-shaped jaws ; ” 5 whilst the females use 
2 These organs in the male often differ in closely-allied species, and 
afford excellent specific characters. Bnt their importance, under a 
functional point of view, as Mr. E. MacLachlan has remarked to me, 
has probably been overrated. It has been suggested, that slight dif- 
ferences in these organs would suffice to prevent the intercrossing of 
well-marked varieties or incipient species, and would thus aid in their 
development. That this can hardly be the case, we may infer from the 
many recorded cases (see for instance, Bronn, ‘ Geschichte der Naturf 
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 together by Dr. Aug. Meyer, 
they coupled , and one pair produced fertile ova. 
3 4 The Practical Entomologist/ Philadelphia, vol. ii. May, 1867, p. 
88 . 
4 Mr. Walsh, ibid. p. 107. 
5 4 Modem Classification of Insects/ vol. ii. 1840, p. 206, 205. Mr. 
Walsh, who called my attention to this double use of the jaws, says 
that he has repeatedly observed this fact. 
