SCOLYTIDZ. 85 
Group. Geuus. species eratained, 3 E 4 E ra 3 Characters 
‘and authority. Z a 5 g 2 E of other organs. 
FY <q & 
T inued) . ‘eon ..| [Trypodendron]. | 3. Hopk. ...... 3 . . { noe and tarsi fringed: 
Gnathotrichus ..| 2. Hopk. 
1. Blandf. ....) .. Q (5) 
Pterocyclon 2. Hopk....... 2 (6) 2 of 
. 2. Blandf. 
Corthylus ...... 2. Hopk....... fe) fe) 
PLATYPODIDES (1). Platypus ...... 2. Hopk....... . . 3 | Abdomen: ¢. 
Several. Blandf. 
[Crossotarsus] ..| 2. Blandf. .... 2 je) res Abdomen: ¢. 
Tesserocerus ....| 2. Blandf. ....| .. io) 3 
(1) The Scolytoplatypodides and Platypodides exhibit sexual differences in the mouth-parts, front, pro- 
thorax, and legs, which cannot be tabulated as being deviations from a simple type in one or the 
other sex. 
(2) The habits of several species of these genera are so well known as to exclude the possibility of mistakes, 
even without actual dissection. 
(3) The few additional hairs on the front of D. terebrans Q form an unimportant character “of little value” 
(Hopk.). 
(4) The references are to the sexual determinations in Eichhoff’s ‘ Die europiiischen Borkenkéfer,’ and not his 
‘ Ratio Tomicinorum.’ 
(s) Sexual characters may be present in the elytra, but have not been definitely assigned. 
(6) The front of P. fasciatum has a slight impression in the male, an unimportant exception. 
This Table, which might be greatly lengthened by the inclusion of many genera and 
species in which the application of secondary sexual characters, though not ascertained 
by dissection, is hardly a matter of doubt, shows that such characters, exhibited by the 
elytra, are confined to the males, as far as is known. Till an exception be proved, 
elytral characters may therefore be assumed to be a constant male character throughout 
the Scolytide. The same applies to the less frequent abdominal characters, 
Frontal and antennal characters appear, when well-defined, to be a constant distin- 
guishing mark of the males in Scolytoplatypodides, Scolytides, Hylesinides, and Hexa- 
colides. ‘They change in the Tomicides, being a male characteristic in Tomicus, Trypo- 
dendron, and Pityophthorus minutissimus ; and a female characteristic in other genera 
