512. 



THE DESCENT OF JfAff. 



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 cornutiis (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 

 (Lncamis elaphus) uses his jaws, 

 which are much larger than 

 those of the female, for the same 



Eurpose but probably likewise 

 3r fighting. In one of the sand- 

 wasps (AnunopJiila) the jaws in 

 the two sexes are closely alike, 

 but are used for widely different 

 purposes; the males, as Prof. 

 Westwood observes, " are exceed- 

 ingly ardent, seizins their part- 

 ners round the neck with their 

 sickle-shaped jaws;"J while tho 

 females use these organs for 



V- MT1 ;i_hanlcR anfl 



DU1 rowing 



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 arc. armed with a 



their development. That this can hardly be the case, we may infer 

 from the many recorded cases (see, for instance. Broiii), "Geschichte 

 der Natnr," B. ii, 1843, s. 164; and Westwood, "Transact. Ent. 

 Soc.," vol. iii, 1842, p. 195) of distinct species having been observed 

 in nni:>:i. Mr. MacLachlan informs me (vide " Stett. Ent. 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. 



*"The Practical Entomologist," Phila., vol. ii, May, 1867, p. 88. 



fMr. 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 lie has repeatedly observed tMs fact. 



te. 9. Crabrocribrarins. Upper 

 figure male; lower figure femaie. 



