Lucanoid Goleoptera. 79 



head is fully apparent; in the var. minor of the species 

 this character is often wanting. M. impressus assimilates 

 in general form to the allied species M. castaneus and 

 M. foveatus, its coloration, however, is not uniform, a 

 somewhat indistinct black plaga existing on the centre 

 of the prothorax and elytra. The fossa noticed on the 

 head between the eyes in the var. minor, does not appear 

 to exist in the specimen in question. 



Metopodontus Maclellandi. 



Lucamis McLellandi, c?j Hope (var. minor) Tr.Ent. Soc. 



iv. 74. 



Cladognathus qiiadrinodosus , S , Parry (var. max.) Tr. 



Ent. Soc. ser. 3, ii. 22, pi. viii. fig. 4. 



We have here another instance of the difficulty in 

 appreciating species unless the author has before his eyes 

 a series of specimens exhibiting the various gradations 

 of growth in the mandibles. I have already stated that 

 the entire sculpture of a species alters with the condition 

 of these organs ; not so, however, its size ; the outward 

 form of species both with developed and non-developed 

 mandibles being generally found identical, although the 

 sculpture may vary considerably. The present insect 

 affords an excellent illustration of these facts, elucidated 

 from a series of specimens now in my possession, in 

 which the mandibles exhibit four different gradations of 

 development, and had I possessed these specimens when 

 describing G. quadrinodosus, the error alluded to could 

 not have occurred. The very peculiar character of G. 

 quadrinodosus, which is not to be met with in any other 

 insect belonging to the Lucanoid Goleoptera, viz., the 

 being furnished on its vertex -with four distinct tubercles, 

 led me naturally to consider it as a distinct species, dif- 

 fering as it does so greatly in this, as in several other 

 respects, from G. Maclellandi, the latter being totally de- 

 void even of the faintest trace of tubercles. G. Maclellandi 

 may be considered as the lowest development of the 

 species, and be represented as No. 4. In No. 3, the 

 next stage in growth of the mandibles, a trace of the 

 tubercles already exists, which in No. 2 becomes stronger, 

 and in No. 1, represented by G. quadrinodosus, they are 

 exceedingly prominent, and, as I believe, the insect 

 then attains the maximum of growth. 



The female of G. Maclellandi 'has not yet fallen under 

 my notice. 



