Incipient horns are found in not a few cases among the females of these insects, while in others, as in the case of the Reindeer Beetle, they are almost as well developed as in the males. This is what one would expect to find if these outgrowths were the result of inherent variations restrained as to their size by natural selection, which eliminates only when this growth penalizes, by increasing the struggle for existence. As to the actual behaviour of Beetles when sexually excited but very little information is obtainable; but there are records of species the males of which fight with rivals for the possession of females. Wallace saw two males of _Leptorhynchus augustatus_, a Beetle with no name in common speech and a long beak, “fighting for a female, who stood close by busy at her boring. They pushed at each other with their rostra, and clawed and thumped in the greatest rage.” The smaller male, however, “soon ran away, acknowledging himself vanquished.” In this case, it is to be noted, the combatants lacked weapons. With the Stag Beetle it is otherwise, and this species is said to engage in fierce conflicts. Darwin cites an instance where two males were enclosed with one female in a box, when the larger severely pinched the smaller one, until he resigned his pretensions. This being so, it is curious to find that the female, which makes no display of pugnacity, has the stronger jaws. The fact that there are so few records of fighting among male Beetles, and the absence of injury to the highly-polished surfaces of the horns or jaws where these are conspicuously large, seem to indicate that at most no more than a semblance of fighting ever takes place. In a North American Stag Beetle (_Lucanus elaphus_) the jaws, which are greatly developed, are used, Darwin tells us, for seizing the female, but they do not appear to be employed for this purpose in any other species. It might be held that they play the part of terrifying agents, as the eye-spots of Caterpillars and adult Lepidoptera are believed to do. At any rate, they seem to be so used in the case of a Beetle of South Chile (_Chiasmognathus grantii_) wherein the jaws are of great size and have their inner edges toothed. When threatened “he faces round, opens his great jaws, and at the same time stridulates freely.” But this parade of force is evidently no more than “bluffing,” for Darwin, who describes this behaviour, remarks, “the mandibles were not strong enough to pinch my finger so as to cause actual pain.” In the female, it may be remarked, the jaws are quite small.