Memoirs on the coleoptera

TENEBRIONID/E
As a section of the tribe Asidini the Eurafrican species differ from
the American (i) in the marked differences between the sexes,
which, in depressa, become extreme, there being few Coleoptera
in which the sexes become so completely incongruous, (2) in the
more narrowly separated coxae, (3) in the prominence of the inter-
coxal process of the prosternum, which, though occasionally dis-
appearing as in reichei, is nevertheless generally at least traceable,
and as characteristic of the old world species as the deflexion of
in the more slender antennae
the process is of the American, (4)
with the tenth joint more abruptly enlarged,
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a character which
is however subject to some exceptions in both regions, (5) in the
almost universally less developed gular pedestal of the mentum,
and (6) in peculiarities of sculpture as developed in the more
typical species, the tufted tubercles being unknown among the
American representatives, although suggested perhaps in the very
aberrant Mexican fasciculata Champ. The tendency to become
coated with indurated and closely adherent mud is also much
more characteristic of the European than of the American species,
there being however some exceptions among our genera and many
notable exceptions in the Mediterranean fauna, such as depressa,
dissimilis, goudoti, politicollis, sicula and other related forms,
among which there are assuredly several Asida.
genera distinct from
Astrotus Lee.
The few known species of this genus have the surface throughout
coated densely with indurated earthy matter, which becomes vir-
tually an almost integral part of the integuments and is very difficult
to remove; through this coating the minute setae protrude. The
fact that these hairs are not involved in the coating, but are maintained
clean and free from such extraneous substance, proves them
to possess a tactile function of direct utility as a means of recog-
nizing external impact; they are therefore subject to the laws of
natural selection and the diverse forms that they assume in the
various genera are of greater
value in a taxonomic sense than is
usually admitted. This is a general law affecting setae growing
from punctures throughout the Coleoptera, but does not concern
so evidently the fine dense pile sometimes present, as on the under
surface of the Melolonthinse for example.
T. L. Casey, Mem, Col. Ill, Feb. 1912.