SCOLYTIDAE. 521 



Tribe III.— HYLIJRGIIVI. 



In this tribe the liead is exposed, not covered by a prolongation 

 of the prothorax; the latter is truncate in front or but slig-htly 

 rounded, and not differently sculptured ; beak short and stout. 

 The antennae vary in form according to the group, and in Hylastes 

 assume very mucli the same form as in Cossonidse, to which some 

 of these insects bear a strong resemblance. They may be distin- 

 guislied, however, by the compressed and serrate or spinulose tibiae. 



The third joint of the tarsi is frequently dilated and bilobed, 

 and the fourth joint, less conspicuous than in the preceding tribes, 

 is sometimes quite indistinct. The first and second ventral seg- 

 ments are always separated by a well-defined straight suture, more 

 deeply impressed than in Tomicini. 



The prothorax is bisinuate behind, with a well-defined ante- 

 scutellar angle in some of the species of all the groups except 

 Hylastes. They thus manifest a tendency to the Anthribidie 

 (Choragus, etc.), as Hylastes does towards the Cossonidae. 



In several genera the front coxae are separated by the pro- 

 sternum, and in Dendroctonus and the allied European genera 

 Hylurgus and Blastophagus the second and third ventral sutures 

 are curved backwards at the sides. In Hylastes the prosternum 

 is deeply excavated for the reception of the short beak. In all 

 these characters resemblances arc seen to different tribes of Cur- 

 culionidffi. 



Our genera indicate the following groups: — 



Club oval, annulated, scarcely compressed. 2. 



Club strongly compressed, not annulated, pubescent on both sides. 



POLYCJRAPHI. 



2. Joints of club separated. Phlceotribi. 

 Joints of club closely connate as usual. 3. 



3. First and fifth ventral segments elongated, seutelhiin not depressed. 4. 

 Ventral segments nearly equal and scuteiluni de^jressed. Hylukgi. 



4. Prosternum very short, funicle with few joints. Crypturgi. 

 Prosternum excavated ; funicle 7-jointed. Hylastes. 



Group I. — Polygraph!. 



This group is sufficiently defined by the club of the antennas 

 being large, strongl)'- compressed, pubescent and sensitive, and 

 without sutures on both sides, and by the antennae being inserted 

 as usual at the sides of the front. The tibiae are broadly dilated, 



