1892.] 



THE BRITISH NATURALIST. 



139 



mandibles, palpi, and antennae. In a great many beetles the head of 

 the male is larger, and more especially broader, than that of the 

 opposite sex, and as examples the following insects may be cited: — 

 Many of the vStaphylinidae, as Quedius cnientiis, Velleius dilatattis, 

 Creophilus maxillosiis, Emus hirtus, Ocyptis oleiis, some Philonthi (splendens, 

 ceiietis, umbratilis, cephalotes), and Cajiiis xantholo-ma, in all of which the 

 larger head tends to become quadrangular, that of the female being 

 oval or triangular-ovate; several Steni, notably Steiius iiicamis; 

 Oxyponis nifiis ; some Oxyteli; Anthopliagus nlpiniis; Progiiatha 

 quadricornis ; some species of Ips (qiuidvipitnctata) and Rhizophagns 

 (depresstts, nitidulus, dispar); several members of the family 

 Telephoridae or soldier beetles, such as Rhagonycha fnlva, pallida, and 

 eloiigata, which also have the eyes more prominent in the male, most 

 Malthiniis and MnltJwdes, in which the broadened head is also strongly 

 constricted behind into a neck ; Dolichosoma, and Dnsytes. But it is 

 in Lticamis cerviis that this portion of the body reaches its greatest 

 development in British beetles, in order to support the enormous 

 mandibles which are often more than half the length of the insect 

 itself, and which from being curved, forked at the tip, and furnished 

 with a strong antler-like tooth at about the middle of the inner side 

 have caused the popular name " Stag-beetle " as well as the specific 

 name cevvns of Linnaeus to be applied to this species. Specimens of 

 the male are frequent in which the mandibles do not reach such great 

 development, in which they are shorter, nearly straight, sharp and 

 not forked at the apex, and with a tooth and some crenulations near 

 the base on the inside, but in all cases these are very different from 

 the small but very strong and sharp mandibles of the female, which, 

 unlike those of the male, are capable of inflicting a very severe bite. 

 Opinions differ as to the use of the enormously developed jaws of the 

 male, but as they have been known in confinement to use them to 

 crush fruit the probability is that in a state of nature they are used 

 for such a purpose and for rasping the young bark off trees in order 

 that they may feed upon the sap. In the allied species, Dorcus 

 pavallelopipedits, the head of the male is also larger than that of the 

 female and is furnished with longer mandibles, each of which has a 

 horn-like tooth (replaced by a blunt tubercle in the female) projecting 

 from the middle. Contrary to the usual rule the head of the male 

 Apodcrus covyli is narrower than that of the female, and more con- 

 tracted behind. Leaving for the present any further consideration of 

 the mandibles we may notice that several species, more especially 

 among the Brachelytra, have the heads of the males marked with a 

 depression between the eyes ; such is the case in Homalota grniiiiiiicola, 

 occtUta and lincans; and while the female of Homalota divisa has the 

 head (and thorax also) slightly hollowed, the male has these portions 



