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CHAP. XIV.] THE NEOTROPICAL REGION. 75
islands. Of Cerambycidae there are 16 genera, 2 of which range
all over America, 4 are Neotropical, 1 South American only,
while the following are confined to the islands, Merostenus,
Pentomacrus, and Ehuriola (Jamaica) ; Bromiades (Cuba)
Trichrous, Heterops, and Pceciloderma (Antilles). One genus,
Smod,icum, is widely spread, having a species in Carolina, 1 in
South America, 1 in Hayti, and 1 in West Africa. Of Lamiidse
there are 14 genera, 8 of which are Neotropical, 1 common to
Central America and Mexico, 1 to the United States "and Cuba,
while 2, Proecha and Phidola, are confined to Cuba. Several of
the genera are curiously distributed ; Spalacopsis is South
American, with 4 species in Cuba and Tropical Africa ; Lago-
cheirus is Neotropical, with a species in Australia ; while Lepto-
stilus is characteristic of the Antilles and North America, with
a few species in South America, and one in New Zealand.
These cases of erratic distribution, so opposed to the general
series of phenomena among which they occur, must be held to
be sufficiently explained by the great antiquity of these groups
and their former wide distribution. They may be supposed to
be the remnants of types, now dying out, which were once, like
Callichroma, Clytus, and many others, almost universally dis-
tributed.
All the peculiar Antillean genera of Cerambycidse and La-
miidae are allied to Neotropical forms. The peculiar Prionidae,
however, are mostly allied to Mexican and North American
groups, and one, Monodesmus, belongs to a group all the other
genera of which inhabit the East Indies and South Africa.
Land-shells.—This subject has already been generally treated
under the Region, of which, in this class of animals, the Antilles
form so important a part. We must therefore now confine our-
selves mainly to the internal distribution of the genera, and to
a few remarks on the general bearing of the facts.
The excessive and altogether unexampled productiveness of
the West Indian islands in land-shells, may be traced to two
main sets of causes. The first and least known, consist of the
peculiar influences and conditions which render islands always
more productive than continents. Whatever these conditions