INTRODUCTION". 7 



and their palpi are entirely hidden, and there is no supporting 

 peduncle projecting from the submentum. But in some genera 

 there is a very short and broad peduncle, and in such cases the 

 base of the maxilla is visible on each side ; the maxillar}' palpi, 

 however, are always concealed when the mouth is closed, though 

 an insect will sometimes die with its palpi exserted beyond the 

 front margin of the mentum. 



In the Phanerogn'athi the mentum assumes much more 

 varied shapes (tig. 3^ 5, c, d) and is nearly always supported on 

 a marked process emitted by the submetitum. In these insects 

 the maxillary palpi are clearly visible, lying on each side of the 

 mentum, and the mandibles are much more slender and pointed ; 

 but this does not apply to the Sii'alix.i:, in which the condition 

 of the mouth-parts is quite abnormal (tig. 3, <?), tlie peduncle 

 having apparently become fused "with the edges of the emargina- 

 tion of the submentum in which it normally lies, so that the 

 buccal cavity is reduced to a transverse slit at the apex of the 

 rostrum, only the mandibles being visible. An allied Eastern 

 genus, Cnjptoderma (0.r>jrhi/nchiis), presents what appears to be 

 a transitional condition in this direction. 



7ns. rro^- -yrt. rrjx • ms jr s ^<-S. ! m.S. 



ep 



a. 



L. 



Fig. 4. — Apex of rostrum of: a, h, Asti/cus chiy/sochlorus, WiecL, ventral and 

 dorsal views ; c, d, Episuiiius subnitenx, i\Jshl., ventral and dorsal views; 

 ma, mandible ; m..s., mandibular scar ; mc, mentuin ; cp, epistome. 



The maxillfe are always slender in those species in which thev 

 are hidden by the mentum, but in the other section they are 

 often a good deal stouter, and especially in an Australian sub- 

 family, the AMrcTEKi>'.i;, in which they are broad and fused to 

 the sides of the mentum. They have normally only a single 

 lobe, and even this is evanescent in the species with a very 

 slender rostrum. The place of the missing outer lobe is occupied 

 by the palpus. 



Among the Adelogxathi the mandibles present a character 

 the significance of which was first explained by Lacordaire (Gen. 

 Coleop. vi, p. 5), and was subsequently shown by Leconte to be 

 of considerable taxonomic importance. If the mandibles of one 

 of the BrackyderiNtE or OTiORRHYJfCHiN^^ be examined from 

 in front, there will be observed on each a more or less rounded 

 or oval area, which is sometimes merely flattened, but is more 

 often slightly hollowed (fig. 4). The edge of this area is nearly 



