READING PUBLIC MUSEUM AND ART GALLERY

vi Introd1tction
the tribe to be arranged into two groups, namely, those in which
the pronotum is nal'l'ower at apex than at the base, as in Lochmaeoeles,
HYPs'ioma, and the like, and those in which the opposite
condition prevails, as in Oncide1"es, Taricanns, and allies. Nevertheless,
certain genera" such as Cacostola, where either condition
may occur or in which the base and apex are of equal width, connect
the two divisions, thus making the use of subtribes unwarranted.
In the first of these groups, several forms of pronotum occur ;
first, conical, in which the sides are straight and regularly and
distinctly narrowed to the apex (as in Hypsclo'11t1t8) ; second, subconical,
in which the sides are distinctly arcuate, but strongly
narrowed anteriorly (as in Marensis) ; third, those which have the
sides tumid before and behind middle but still much narrower at
apex than at base (as in Loch1naeoclcs) ; and, finally, cylindrical,
the sides straight, nearly parallel, (lschioccntra). Intergrading
forms can be found between most of these groups.
'rhe antennae are variable in length and in thickness as well
as in specialization of the scape, and the third and eleventh segments
between sexes, species, and genera. Probably most important
in distinguishing the genera is the third segment of the antonnae.
In many genera, this segment is bisinuous, that is, curved
npward near the base and in tIle opposite direction apically (Hyps'ioma)
; in others it is simply straight (lschiocentra), or occasionally
arcuate (Jatltcsia). In scattered cases, this may be swollen
in various ways but usually only in the males; in several Oncideres,
for example, the segment is tumid evenly throughout its
length. In Clavidcs1nus, on the otber hand, it is strongly expanded
towards its apex.
Also of great significance in the distinction of genera are the
elytra. Frequently, these organs are granulate or granulate-punctate
over the basal portions, or the granules may be confined to the
tumid areas (referred to as the basal gibbosities) or to the humeri.
Or, even in genera closely related to granulate forms, the sculpturing
will consist of simple punctures. The humeri occasionally
are sh'ikingly modified, bearing crests (l'yphlocerus, Truncatoides,
and Lesbates acro1nii), or are conical (Agar'itha), but are most
variable in the degree of prominence. As a whole, the apices are
simply rounded, either together or separately. Only in Ecthoea
is an exception found; here there are two long rounded teeth on
each apex.