54 



THE SCOLYTID BEETLES. 



Head. The elements of the adult head recognizable in the young pupa 

 are the antennae, mandibles, maxillae, labium, and what appears to 

 be a well-developed labrum, which extends to the middle of the man- 

 dibles. Evidently, however, this does not represent the labrum or 

 even the clypeus, but is a pad to accommodate the development of 



the long epistomal bristles. The frontal spines in examples repre- 

 senting different divisions and species are variable in size and position 

 and are of considerable taxonomic importance. The antennae do not 

 extend to the base of the pronotum or scarcely beyond the mouth 

 parts, and the club does not extend beyond the lateral margins of the 

 pronotum. 



