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 cor nidus (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 elaphus) 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 

 (AmmojiMla) 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. But their importance, under a 

 functional point of view, as Mr. K. 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, ' Gesehichte 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 together by Dr. Aug. Meyer, 

 they coupled, and one pair produced fertile ova. 



s ' The Practical Entomologist,' Philadelphia, vol. ii. May,^ 1867, 

 p. 88. 



4 Mr. Walsh, ibid. p. 107. 



5 < Modern 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. 



