CHAP. XIV.] 
THE NEOTROPICAL REGION. 
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islands. Of Cerambycidee 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 Eburiola (Jamaica) ; Bromiades (Cuba) ; 
Trichrous, Heterops, and Pceciloderma (Antilles). One genus, 
Smodicum, is widely spread, having a species in Carolina, 1 in 
South America, 1 in Hayti, and 1 in West Africa. Of Lamiidm 
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, Proechcc and PMdola, 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 Cerambycidee and La- 
miidae are allied to Neotropical forms. The peculiar Prionidee, 
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 
