i86 Memoirs of the Indian Museum. [Vol III, 



The lahriim, or upper lip, is attached to the margin of the cl3^peus, and projects 

 beyond the fold which forms the anterior margin of the head to an extent which often 

 varies considerably in different specimens of a single species. The shape of its 

 anterior margin, too, is only moderately constant, though the minute tooth which it 

 bears in the middle in the genus Gnaphalocnemis and its immediate allies appears to be 

 a character of some importance. In asymmetrical forms the left anterior angle is more 

 or less distinctly prolonged beyond the right even when the right side of the clypeus is 

 more highly developed than the left. Its upper surface is always covered with punc- 

 tures and long hair in specimens which are in really good condition ; and in the Aula- 

 cocyclinae an indistinct ridge usually crosses it transversely not far from the anterior 

 margin. In certain species of Aulacocyclinae eg. Ceracupes fvonticornis and C. austeni) 

 this ridge instead of being indistinct is very pronounced. 



Lower Surface of Head. 

 The only plate on the lower surface of the head, that need be considered here 

 is the mentum, a broadly U-shaped shield situated immediately behind the mouth- 

 appendages. The structure of this plate is of great importance in the Aulacocyclinae 

 in the definition of genera, and in some cases in the definition of species also. In the 

 remaining sub-families it is convenient to refer to the transverse median part of the 

 plate as the central part, and to the whole of the paired side pieces, right back to the 

 posterior margin, as the lateral parts. The former area is usually smooth or more 

 sparsely punctured than are the latter parts, from which it is often separated by a 

 pair of depressions or primary scars. These scars are always more or less round when 

 complete, but more often than not their antero-external margin is imperfectly developed 

 or obsolete, when they appear crescentic, the concavity always facing outwards and 

 forwards. Their presence or absence is a character of importance .for the grouping of 

 genera together ; but they do not seem to be of any use in separating species one from 

 another. In certain genera the whole anterior margin of the central part of the 

 mentum is apt to be depressed ; in others this depression is moved backwards and 

 outwards on to the surface of the mentum, in some genera ' so far as to replace the 

 primary scars , which are obliterated . The pair of depressions thus formed may be termed 

 secondary scars. When so well developed as to obliterate the primary scars these 

 secondary scars are of great importance in classification ; when the primary scars are 

 present as well they may be useful but are less constant, are often found to be 

 only of specific value, and sometimes to exhibit a considerable continuous range of 

 variation within the limits of a single species. 



Prothorax. 

 The whole upper surface of the prothorax is covered by the pronotum. In 

 most species this bears at least a trace of a median groove , which in some species is 

 very pronounced indeed. Differences in the distinctness of this groove are so readily 



' The scars on the mentum of these genera were unfortunately confused with primary scars in my 

 1912 preliminary paper. 



