_ SCOLYTIDES, 119 
appears to be necessary if the old distinctions between the two last-mentioned groups 
are to be retained. ‘These tend to merge one into the other, and it does not seem 
possible to define any one constant character that will separate them. 
The four groups car be thus distinguished :— 
Tibize produced at the upper apical angle beyond the tarsal insertion into a mucro 
or bifid process, sometimes indistinct, except on the anterior pair . . . . Scolytides. 
Tibize never produced above the tarsal insertion into a mucro or process. 
Head subrostrate, visible from above; third tarsal joint usually widened and 
emarginate at apex or bilobed; antennal funiculus 5-7-jointed; prothorax 
not margined at the sides (except in Problechilus) ; anterior cox varying 
in proximity . 6. ee ee ee Hylesinides. 
Head feebly subrostrate, imperfectly concealed by the prothorax ; third tarsal 
joint simple; antennal funiculus 6-jointed; prothorax margined at the 
sides, very finely or obsoletely asperate towards apex ; anterior cox not 
contiguous. 2. 6 8 6 ee ee ee ee ee Hexacolides. 
Head globose, concealed from above by the prothorax ; third tarsal joint simple ; 
anterior cox contiguous ; prothorax rarely margined at the sides; antennal 
funiculus 1-5-jointed (Hylocurus has a 6-jointed funiculus, and the anterior 
coxe not contiguous, but the head is completely concealed from above). . Tomicides. 
As between the Hylesinides and Tomicides, an exception to almost every character 
given can be found in Scolytide from some part of the world; and there has been 
much diversity of opinion as to the group in which certain genera should be placed. 
The only Central-American genus about which there is much ambiguity is Problechilus, 
containing insects of Cryphalus-like form, but with a 7-jointed funiculus and separated 
anterior coxe. | 
Eichhoff includes it in the Tomicides, but it seems as suitably placed in the 
Hylesinides, in which it constitutes the only Central-American genus with a side- 
margin to the prothorax. | 
Group SCOLYTIDES. 
Head subrostrate; eyes oblong, sometimes subemarginate; antenne with seven-jointed funiculus, and oval or 
oblong compressed club. Prothorax usually with a distinct side-margin (not sharply marked in some 
Bothrosterni), its upper surface entirely devoid of elevated granules or asperities, punctured or strigillate ; 
anterior coxe remote. Side-pieces of the metasternum broad. Intercoxal process of the abdomen usually 
blunt and broad. Tibise produced at the upper apical angle into a mucro or bifid process, sometimes 
indistinct, except on the anterior pair. 
The Scolytides, which form a tolerably homogeneous group, distinguished among 
other features by the sculpture of the prothorax, which is never in the least granulate 
or asperate as it is in the majority of Hylesinides, fall into three snbgroups :—. 
Anterior tibiee with the upper border unarmed, and the upper apical angle produced — 
into a curved mucro. 
Abdomen reflexed upwards from the base of the second or third segment ; joints 
of the funiculus simple in both sexes. eee 1 + ee ew ee Scolyti. 
