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498 GEOGRAPHICAL ZOOLOGY. [part iv.
LONGICOENIA. (1,488 Genera, 7,576 Species).
The elegant and admired group of the Longicorn Beetles, is
treated by continental authors as a single family, consisting of
three sub-divisions—the Prionidae, Cerambycidce, and Lamiidse
of English entomologists. These are so closely related, and are
so similar in form, habits, and general distribution, that it will
be best to consider the whole as one group, noticing whatever
peculiarities occur in the separate divisions. The endless
structural differences among these insects, have led to their
being classed in an unusual number of genera, which average
little more than 5 species each ; a number far below that in any
of the other families we have been considering, and probably
below that which obtains in any of the more extensive groups
of animals or plants. This excessive subdivision of the genera,
a large number of which consist of only one or two species,
renders it difficult to determine with precision the relations of
the several regions, since the affinities of these genera for each
other are in many cases undetermined. A group of such
enormous extent as this, can only be properly understood after
years of laborious study ; we must therefore content ourselves
with such results as may be obtained from a general survey of
the group, and from a comparison of the range of the several
genera, by means of a careful tabulation of the mass of details
given in the recent Catalogue of Messrs. Gemminger and Harold
and the noble work of Lacordaire.
The proportionate extent of the three families of Longicorns is
very unequal ; the Prionidse comprising about 7 per cent., the
Cerambycidse 44 per cent., and the Lamiidaj 49 per cent, of the
total number of species ; and the genera are nearly in the same
proportions, being almost exactly 10, 40, and 50 per cent, of the
whole, respectively ;
or, 135 Prionidse, 609 Cerambycidse, and 746
Lamiidse. The several regions, however, present marked differ-
ences in their proportions of these families. In the two North
Temperate regions, the Cerambycidse are considerably more
numerous than the Lamiidai, in the proportion of about 12 to