Chap. X. Coleoptera. 299 



1'he caees hitherto given refer to the Lamellicorns, but the 

 males of some few other beetles, belonging to two widely distinct 

 groups, namely, the Ourculionidse and tjtaphylinidse, are fur- 

 nished with horns— in the former on the lower surface of the 

 body,°"in the latter ou the upper surface of the head and thorax. 

 In the StaphylinidsB, the horns of the males are extraordinarily 

 ■variable in the same species, just as we have seen with the 

 Lamellicorns. In Siagoniiim we have a case of dimorphism, 

 for the males can be divided into two sets, differing greatly 

 in the size of their bodies and in the development of their 

 horns, without intermediate gradations. In a species of Bledius 

 (fig. 23), also belonging to the Staphylinidse, Professor Westwood 



Fig. 23. Bledius taurus, magnified. Left-hand figure, male; right -liand figure female. 



states that, " male specimens can be found in the same locality 

 " in which the central horn of the thorax is very large, but the 

 " horns of the head quite rudimental; and others, in which the 

 "thoracic horn is much shorter, whilst the protuberances on 

 " the head are long."" Here we apparently have a case of 

 compensation, which throws light on that just given of the 

 supposed loss of the upper horns by the males of Onitis. 



Law of Battle. — Some male beetles, which seem ill-fitted for 

 fighting, nevertheless engage in conflicts for the possession of 

 the females. Mr. Wallace"* saw two males of Leptm-hynchus 

 angustatua, a linear beetle with a much elongated rostrum, 

 " fighting for a female, who stood close by busy at her borintr. 

 " They pushed at each other with their rostra, and clawed and 

 " thumped, apparently in the greatest rage." The smaller male, 

 however, " soon ran away, acknowledging himself vanquished." 

 In some few cases male beetles are well adapted for fighting, by 

 possessing great toothed mandibles, much larger than those of 

 the females. This is the case with the common stag-beetle 

 (^Lucanus cervus), the males of which emerge from the pupal 

 state about a week before the other sex, so that several may 

 often be seen pursuing the same female. At this season they 



"^ Kirby and Spence, ' latroduct. gonium in an intermediate condi- 



Entomolog.' voi. iii. p. 329. tion, so that the dimorphism is not 



6' ' Modern Classification of In- strict, 



sects,' vol. i. p. 172: Siagonium, " 'The Malay Archipelago,' vol. 



p. 172. In the British Museum I ii 1869, p. 276. Riley, Sixth ' Rapcrt 



noticed one male specimen of Sia- on insects of Missouri,' 1874, p. 115. 



