OF WASHINGTON. 147 
labrum and other parts of the anterior area of the larval head, 
including the epipharynx, possess certain features common 
to such a wide range of species, that they must be recognized, 
especially in the coleopterous larvae, as possessing characters 
of prime importance for future systematic work, and, it seems 
to me, offer a rich field for original research. 
EXPLANATION OF PLATE IV. MOUTHPARTS OF 
1. Head of Larva (Dendroctonus ponder osae), dorsal view. 
2. Same ventral view. 
3. Same oral view. 
4. Same lateral view. 
5. Same front, clypeus and labrum. 
6. Maxillae of D. valens, showing first and second with 
muscular structures. 
7. Front, clypeus and labrum of D. terebrans. 
8. Front, clypeus and labrum anatomy of D. ualens. 
9. Front, epistoma and labrum of adult D. brevicomis, var. 
barberi. 
ABBREVIATIONS. 
a. ang ......... Anterior angle of mandible. 
ac ............ Antecoxal piece. 
ant ........... Antenna. 
ap . . . , ........ Apical palpi of epipharynx. 
b. rdg. e ....... Basal ridge of epistoma. 
b. rdg. m ........ Basal ridge of mandible. 
b. tub ......... Basal tubercle of mandible. 
Cl ............. Clypeus. 
C. i .......... ist Clypeus. 
C. 2 .......... 2d Clypeus. 
c ............. Cardo. 
d. art. of m. . .Dorsal articulation of mandible. 
E ............ Epicranium. 
epi .......... Epipharynx. 
est ........... Epistoma. 
esu ............ Epicranial suture. 
F ............. Front. 
fl or ap ........ Fontenal (or apex) of frontal area. 
fs ............ Frontal suture. 
G ............ Gena. 
Gu... ..Gula. 
