i8 94 .] 



THE BRITISH NATURALIST. 



259 



genus Platymesomus the middle tibiae of the male are dilated. Chei- 

 opachus has the posterior femora of the males and the anterior femora 

 of the females thickened. 



In Coleoptera the most remarkable example is CEdemera nobilis, in 

 which the hind thighs project from the sides like huge knobs ; others 

 are Osphya bipunctata, Oncomera femorata, Necrodes littoralis, Stenus 

 Juno, Megarthrus denticollis, Telmatophilus caricis, and Rhynchites 

 betulae ; all the males of these have the hind thighs much thickened. 

 In the males of Clytus the hind thighs are much elongated, and the 

 same sex of Callidinum alni has the hind thighs greatly curved. The 

 males of Anthophagus have the anterior tibiae emarginate. The little 

 genus Bryaxis presents some curious sexual modifications of the 

 anterior trochanters ; for the study of which and of the various and 

 numerous sexual characters presented by the leg's and feet of the 

 Coleoptera, the reader is referred to the excellent article by Dr. Ellis 

 on the " Secondary Sexual Characters of the British Coleoptera," 

 contained in the British Naturalist, vol. ii., pages 209 and 233. 



In.Diptera the male of Ochthera mantis has a most peculiar pair of 

 front legs, being very much thickened in the middle. In Empis the 

 males generally have longer legs than the females. In the males of the 

 Dolichopidae the tarsi are often peculiarly formed or marked, or the 

 femora fringed beneath, or the tibiae thickened, mostly the hind pair, 

 which have also a sort of variole in some. In Dolichopus plumiper, 

 pennatus, and popularis the middle tarsi are dilated and feathered. 



VIII. — Disparity in Heads. 



This may be especially seen in the Coleoptera, several males of which 

 bear upon their head horns of various degrees of development, especially 

 in the genus Onthophagus. In Onthophagus vacca the horn is straight ; 

 while in taurus, instead of a horn springing from the middle of the 

 head, we have the two extremities developed into long curved horns 

 like those of a Spanish ox. In ovatus alone of the British species is 

 the horn absent. The male of Copris lunaris is also furnished with a 

 horn ; as are, also, those of Odontaeus mobilicornis, Sinodendron 

 cylindricum, and some of the Bledii. The males of the genera 

 Ennearthron and Gnathocerus have two short horns in the clypeus. 

 Many species of Cis have the clypeus deeply notched in the male ; 

 whilst those of the Malachii have the head deeply and transversely 

 impressed. In Hymenoptera the male of Cerocephala formiciformis 

 has a curiously tricornuted head ; and the female of Cratomus 

 megacephalus has an unusually large head. 



IX. — Disparity of Jaws. 

 This may be best seen in the Coleoptera. The males of Lucanus, 



