FAUNISTIC PROBLEMS 
221 
of the genus Pelobates which inhabit Europe. Only a 
single species (P. syriacus) has been discovered in Asia 
Minor. The others extend from western Europe to the 
Caspian. Another genus (Pelodytes) of the family Pelo- 
batidae has one species in Portugal and a second in the 
Caucasus. All the other genera of the family are found in 
the East, and are more remotely akin to Scaphiopus than 
Pelobates is. Hence we may conclude that the distribution 
of these two genera is distinctly favourable to the suggested 
trans-Atlantic land bridge. 
Another interesting amphibian that I have alluded to 
(p. 137) is the newt Spelerpes, which, with the exception of 
a single European species, is peculiar to America (see Fig. 8). 
The centre of dispersal certainly lies in Mexico, from which 
country various sections have spread northward into the 
States, southward as far as Peru, and eastward to the island of 
Haiti. That this discontinuous distribution could not have 
been brought about under existing geographical conditions is 
evident, nevertheless, since no fossil Spelerpes are known, we 
can only judge of the age of the genus from its distribution. 
Hr. Gadow * suggests the Oligocene Period, and thinks that a 
north-Atlantic land connection, such as the one I have de¬ 
scribed in the first chapter of this work, from Labrador to 
Scotland via Greenland, might have brought about the exist¬ 
ing range of Spelerpes. Since the single European species 
inhabits only Sardinia and the mountains bordering the Gulf 
of Genoa, while most suitable ground for its existence is found 
further north, I cannot admit that Spelerpes fuscus reached 
Europe in that manner. The land bridge by which it crossed 
the Atlantic must have lain much further south. 
I have already alluded to the fact (p. 173), that there 
is apparently a south-western and a south-eastern form 
of the American glass snake (Ophisaurus ventralis), and 
that both of them extend northward for considerable dis¬ 
tances. The only other members of the genus are the 
European glass snake (Ophisaurus apus), which inhabits the 
Mediterranean region and is very like the American, and the 
Asiatic species, which is found from the eastern Himalayas 
to Burma. 
* Gadow, H., “ Mexican Amphibians and Reptiles,” p. 244. 
