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CHAP. xiv.J THE NEOTROPICAL REGION. 57
Buprestidee.—In this family there are no peculiar genera.
All the large South American groups are absent, the only im-
portant and characteristic genus being Stenogaster.
Longicorns.—This important group is largely developed, the
country being well adapted to them ; and their distribution
presents some features of interest.
In the Prionidse there are 6 peculiar genera, the largest being
Holonotus with 3 species ; two others, Derotraclius and Mallaspis,
are characteristic ; 3 more are common to South America, and 1
to Cuba. The Cerambycidse are much more numerous, and there
are 24 peculiar genera, the most important being Sphenothecus,
Entomosterna, and Cyphosterna ; while Crioprosopus and Ifetalep-
tus are characteristic of the sub-region, although extending into
South America ; about 12 Neotropical genera extend to Mexico
or Guatemala, while 12 more stop short, as far as yet known, at
Nicaragua. Lamiidse have a very similar distribution ; 13 genera
are peculiar, the most important being Monilema, Hamatoderus,
and Carneades, wliile Phcea and Lagochirus are characteristic.
About sixteen typical Neotropical genera extend to Mexico, and
15 more only reach Nicaragua, among which are such important
genera as Anisopus, Leptwgus, and Callia.
The land-shells are not sufficiently known to furnish any
corresponding results. They are however mostly of South
American genera, and have comparatively little affinity for those
of the Antilles.
Relations of the Mexican sub -region to the North and South
American Continents.—The sudden appearance of numerous
South American forms of Edentata in temperate North America,
in Post-Tertiary times, as narrated in Chapter VII., together
with such, facts as the occurrence of a considerable number
of identical species of sea fish on the two sides of the Central
American isthmus, render it almost certain that the union of
North and South America is comparatively a recent occur-
rance, and that during the Miocene and Pliocene periods, they
were separated by a wide arm of the sea. The low country
of Nicaragua was probably the part submerged, leaving the
highlands of Mexico and Guatemala still united with the North