392 
GEOGRAPHICAL ZOOLOGY. 
[part IV. 
distribution. Their lieacl-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, 
Soutli 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 Pseudopus, whose two species now 
inhabit South-eastern Europe and the Khasya Hills in Assam 
respectively. 
The genera are, — Covdylus , Pseudocordylus , Platysaurns, 
Cordylosaurus , Pleurostrichus, 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; Gerrkonotus (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 Pseud,opus, as above stated, 
in South-east Europe and the Khasya Hills. 
