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392 GEOGRAPHICAL ZOOLOGY. [part iv.
distribution. Their head-quarters is the Ethiopian region,
which contains more than half the known genera and species,
most of which are found in South Africa and several in Mada-
gascar. Next to Africa the largest number of genera and species
are found in Mexico and Central America,with a few in the Antilles,
South America, and California, and even as far north as British
Columbia. Three of the genera form a distinct sub-group—the
Glass Snakes,—the four species composing it being located in
North Africa, North America, South-eastern Europe, and the
Khasya Hills.
The prominent fact in the distribution of this family is, that
the mass of the genera and species form two groups, one in South
Africa, the other in Mexico,—countries between which it would
be difficult to imagine any means of communication. We have
here, probably, an example of a once much more extensive group,
widely distributed over the globe, and which has continued to
maintain itself only in those districts especially adapted to its
peculiar type of organization. This must undoubtedly have
been the case with the genus Fseudopus, whose two species now
inhabit South-eastern Europe and the Khasya Hills in Assam
respectively.
The genera are,— Cordylus, Pscudocordylus, Platysaurus,
Cordylosaurus, Fleurostrichus, and Saurophis, confined to South
Africa ; Zonurus, South and East Africa and Madagascar ; Ger-
rhosaurus, ranges over the whole Ethiopian region ; Cicigna is
confined to Madagascar; Gerrhonotus (22 sp.), ranges from
British Columbia, California, and Texas, to Cuba and South
America, but is most abundant in Mexico and Central America ;
Abronia and Barissia, are two genera of doubtful distinctness,
peculiar to Mexico ; Ophisaurus (the Glass Snake) is found in
the Southern United States as far as Virginia ; the allied genus
Hyalosaurus in North Africa ; and Pseudopus, as above stated,
in South-east Europe and the Khasya Hills.