INSECTS. 273 



Walsh' 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 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." 

 One of the stag^eetles 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 (Ammophila) the jaws in the two sexes are closely 

 alike, but are used for widely different purposes: the males, as 

 Professor Westwood observes, "are exceedingly ardent, seizing 

 "their partners round the neck with their sickle-shaped jaws;"' 

 whilst 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 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 circumstance that the female 

 of some water-beetles (Dytiscus) have their elytra deeply 

 grooved, and in Acilius sulcatus 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 purpose." In the male of Crabro cribrarius (fig. 

 9), it is the tibia which is dilated into a broad horny plate, 

 with minute membranous dots, giving to it a singular appear- 

 ance like that of a riddle.' In the male of Penthe (a genus of 



vol. ill. 1842, p. 195) of distinct species having been observed in union. 

 Mr. MacLaohlan informs me (vide 'Stett. Bnt. Zeitung,' 1867, s. 155) 

 that when several species of Phryganidae, which present strongly- 

 pronounced differences of this kind, were confined together by Dr. 

 Aug. Meyer, they coupled, and one pair produced fertile ova. 

 3 'The Practical Entomologist, Philadelphia, vol. ii. May, 1867, p. 88. 



* Mr. Walsh, ibid. p. 107. 



■^ '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. 



• 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 in- 

 termediate gradations between the sulcated or punctured, and the 

 quite smooth elytra have been observed. See Dr. H. Schaum, as 

 quoted in the 'Zoologist,' vol. v.-vi. 1847-48, p. 1896. Also Kirby and 

 Spence, 'Introduction to Entomology,' vol. iii. 1826, p. 305. 



' Westwood, 'Modern Class, vol. ii. p. 193. The following statement 

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