DE. F. LEUTHNEE ON THE ODOXTOLABINI. 391 



trispinose, with two deep concavities ; while in the small males the sides are 

 convex, as in the females (comp. 0. alces, PI. LXXXIX. figs. 1, 7, and 

 0. lacordairii, PI. XCIV. figs. 1, 2, 5, 6, &c.). 



ig) The breadth of the prothorax often varies, which considerably affects its out- 

 line, as, for instance, in 0. hiirmeisteri (comp. PL XCII. figs. 5, 6). 



{h) In many species the form of the prosternal process is also variable. 



(6) In the elytra. 



[i) These are sometimes strongly convex and sometimes flattened (as in 0. lati- 

 peniiis). 



{Jc) The sculpture. In the Dorcini, for example, Eurijtrachelus titan, Boisd., 

 E. tityus, Hope, and Dorcus dehaani, Hope, D. parry i. Thorns., and B. musimon, Gene, 

 the large males have smooth elytra ; and the small males ridged elytra, like the females 

 (pterygo-dimorphism). 



(!) Coloration (0. luoUastoni, PI. XCIII. fig. 6, 7), &c. 



(7) In the shape and armature of the front tibia; (a specific character). 



In the Odontolabini large (telodont) specimens have generally fewer spines than small 

 ones (in 0. burmeisteri, 0. alces. Sec). 



(8) In the armature of the four hind tibiae (a family character). 



In Cladognathits giraffa and C. confucms the middle spine of the hind tibiae is wanting 

 in small males. This is likewise the case in some species of the genus jEgus. 



Hence it follows, as an unavoidable conclusion, that every morphological character 

 proves, when thoroughly tested, to be variable in one species or another, a result of 

 great importance to systematic morphology. 



(2) Variability and Polymorphism in the Mandibles. 



Every one is well acquainted with our indigenous Stag-Beetle {Lucanus cervus) and 

 with its very different female. This species varies so much in size that the older 

 authors naturally regarded the small males as belonging to a different species, which 

 they called L. cajjreolus, Fabr. But early in the present century, Koechlin, an entomo- 

 logist residing at Mulhouse, having found a large number of specimens in one locality, 

 endeavoured to show that the small specimens were "not a specially created species," 

 but only a slight variety of the large ones ; and this view has been accepted by later 

 entomologists until the pi-esent day ^ 



If a European entomologist were to collect a long series of males of L. cervus for the 

 purpose, he would be able to satisfy himself that they vary chiefly in size, and that the 

 mandibles of the small males are formed like those of the large males ; the only dif- 

 ferences being that the terminal fork is truncated, and that the occipital crest is obsolete. 

 This would lead him to conclude that the small males are only imperfectly developed 

 specimens. 



' Correspondance entomologique, 1S23. Eemarques sur le Lucane, ou Cerf Yolant. 



