92 RHYNCHOPHORA — SCOLYTIDAE. 



A a. Mentum elongate triangular, very nar- 

 row at base. 



Ligula commencing at base of mentum narrow, parallel- 

 sided, toleral)ly acute in front ; club of antennae oval, very 

 distinctly four-jointed, sutures straight. 



Pityophthorus, Eich. 



jB h, Mentum rather long, slightly dilated 

 in front. 



Ligula commencing near l3ase of mentum, narrow, nearly 

 parallel-sided, rounded in front ; similar in other respects 

 to Xyleborus. Dryocaetes, Eich. 



jB jB. First joint of maxillary palpi very large, 

 inflated. 



Ligula commencing near anterior third part of mentum, 

 narrow, oblong oval, apex acute ; club of antennae ovoid, 

 distinctly jointed, sutures straight. Xylehorus, Eich. 



II, Funiculus of antennae with four joints. 



1. Eyes narrow, entire. 



Mentum elongate, gradually dilated and nearly rounded 

 in front ; joints of labial palpi gradually smaller ; club of 

 antennae compressed, oval, shewing fine straight or curved 

 sutures ; scutellum very small ; apical declivity of elytra 

 rounded ; body covered with fine hairs and generally with 

 some scales. Cryphalus, Er. 



2, Eyes oblong-ovate, deeply emarginate. 



Mentum very elongate, gradually dilated in front, ante- 

 rior margin angular in middle ; first two joints of labial 

 palpi equal, third very small ; club of antennae compact, 

 oblong oval; scutellum moderately large, triangular; apical 

 declivity of elytra rounded ; second abdominal segment a 

 little longer than each of the two following ones. 



Try])odendron, Stepli. 



III, Funiculus of antennae with three joints. 



Mentum elongate, parallel-sided; first two joints of labial 

 palpi equal, third very small ; funiculus of antennae with 

 first joint very large, second and third transverse, equal, 

 club very large, compressed, oval, shewing traces of sutures ; 

 apical declivity of elytra rounded. H y p othcnemus, Westw. 



b. Head not globular, visible from above. 



