392 DR. P. LEUTHNBE ON THE ODONTOLABINl. 



But an entomologist who collected a long series of Cladognathus or Odontolahis in 

 their native haunts would arrive at very different results. If collecting in Further 

 India or the Sunda Islands, for instance, he would find such great variations in the 

 mandibles of the males that he M'ould be inclined at first, like the older authors, to 

 regard them as belonging to several distinct species, till some fortunate accident 

 enabled him to obtain a complete transitional series from one extreme form to the 

 other, and he discovered that the same variations occurred in several allied species. 



He would next discover that the middle-sized forms have generally stronger and 

 thicker mandibles than the largest and smallest, and that these species could not be 

 considered simply variable, like the Lucanini and Dorcini, but must be regarded as 

 polymorphic ^ 



Thus Neolucanus castanopteriis^ constantly exhibits only one form of mandibles 

 (PI. LXXXIV. fig. 13), iV". smmdersi has two forms (PI. LXXXV. figs. 13, 16), Odonto- 

 lahis siva has three forms (PL LXXXVI. figs. 1, 3, 6), which are much more 

 distinct in 0. brookeanus (PI. XCV. figs. 13-15), while 0. alces exhibits four forms 

 (PI. LXXXIX. figs. 1, 3, 5, 6). 



As already mentioned, these stages are completely connected by transitional forms in 

 a number of species (for instance, in 0. alces and Hetcrochthes andamanensis). But 

 in other species this never occurs. In 0. hrookeatms no transitional forms between A 

 (PI. XCV. fig. 13) and B (fig. 14) have ever been observed. Nor do we ever meet 

 with transitional forms bridging over the gap between the telodont and mesodont forms 

 of 0. sinensis, 0. cuvera, &c. 



(3) The Question of Species in the Lucatddw. 



Whoever studies the entire group of the Lucanidse, whether from a systematic point 

 of view or from that of comparative morphology, should understand tliat we have here 

 to deal with a plasticity of material which does not allow of our discovering such 

 definitely fixed specific characters as we are accustomed to look for in other groups. 



Wherever we seek for such characters we find them inconstant. It follows that in 

 this family the definition of a species is more extensive than in other groups of insects, 

 and that the descriptions must be differently arranged if they are to be of any perma- 

 nent value. The old authors contented themselves with drawing up a description of a 

 single specimen. This renders it extremely difficult, if not impossible, to identify many 

 of their species with any certainty, as those only can fully realize who have attempted 

 to work at historical entomology. The study of types is more important in the 

 Lucanidee than in almost any other group, for without this assistance many riddles 

 would remain insoluble. 



As a single specimen gives us a very imperfect idea of a species, we must describe 



' Vide Parry, Trans. Ent. Soo. Lond. (3) ii. p. 6() (note). 



' Also N. laticoUis (PI. LXXXIV. fig. 1) and Odontolahis latipennis (PI. XCVI. flg. 1). 



