The Genus Hylastes, Er. 131 
Comparison of External Features of H. PALLIATUS and H. CUNICULARIUS 
with H. ATER, 
The chief feature for comparison of these three species is the general 
conformation; H. ater is elongate and narrow, H. cunicularius elongate and 
broad, and #. palliatus short and broad. Throughout the structure of each 
the proportions of the various parts correspond with those of the whole 
Thus, the metathorax shows those proportions as also does the 
Certain parts of the external structure, however, afford 
For the 
insects. 
metasternum. 
additional comparative characters, notably the prothorax (Fig. 12). 
dd. 
Ere. 12. = Prethorax: 
a, H. ater. b. H. cunicularius 
HT, palhhatus. ¢; 
sake of brevity, I have summarised the most important features in the 
following table. It should be observed that the mouth-parts of all three 
species are very similar and afford no comparative characters. 
Character 
Length 
Breadth of Elytra 
at base 
Head 
Prothorax 
Metasternum 
Sternite 7 of male 
Colour of mature 
adult 
H, ater 
FH, cunicularius 
HT, palliatus 
4-5 mm. 
IeSeled mim, 
Frontal ridge dis- 
tinct, narrow. 
Longer than broad, 
elongate oval, sides 
sub-parallel. Im- 
puncturatemedian 
line not raised, 
not extending to 
apex. Punctura- 
tion sparse on 
disc. 
Slightly broader than 
long, 
Fovea present. 
Black, shining, 
3°5-5 mm. 
1°5-2 mm. 
Frontal ridge less 
distinct. 
As broad as long but 
varying slightly, 
roundly oval. Im- 
puncturate line 
raised, extending 
to apex. Punc- 
turation uniform 
throughout. 
Markedly 
than long. 
Fovea absent. 
Dark brown to black, 
dull, 
broader 
2°5-4 mm. 
1°3-1°5 mm. 
Frontal ridge more or 
less distinct, broad. 
Broader than long, 
blunt pear-shaped, 
sides tapering an- 
teriorly. Impunc- 
turate line raised, 
not extending to 
apex. Puncturation 
uniform through- | 
out, 
Twice as broad as 
lone. 
Fovea absent. 
Pale brown to dark 
brown. 
