BIRDS OF CENTRAL AMERICA 
251 
neotropical, with certain peculiar endemic forms, the greater 
number among the latter being confined to Mexico and 
Guatemala. 
I alluded above to the fact that the family of tortoises, 
Dermatemydidae, is entirely confined to Central America. 
The only species of the family (Dermatemys mawi) inhabits 
precisely that part of Central America which we have reason 
to believe to be one of its oldest parts, viz., Guatemala and the 
neighbouring Honduras and Yucatan. Several members of 
the family formerly lived in North America. They first ap¬ 
peared in Cretaceous times, and still inhabited the south¬ 
western States during the Eocene Period. It is possible they 
may then have spread to Guatemala, becoming subsequently 
extinct in their centre of dispersal.* Another family which 
I mentioned before (p. 134), the “ snapping turtles ” (Cheli- 
dridae), occur in eastern North America from Mexico to 
Canada. Southward of their range they are found only in 
Guatemala and Ecuador. We have noted examples of a 
similar discontinuous range before. Others will be cited in 
the next chapter. 
More important from a faunistic point of view are such 
creatures, as for instance the snake-like limbless amphibians, 
belonging to the family Coeciliidae. They live in moist ground, 
and lead altogether a burrowing life. Their distribution ought 
to give us, therefore, some valuable hints as to former changes 
of land and water. Dr. Sarasin f looks upon this family as a 
pre-Cretaceous relict, on account of its peculiar discontinuous 
range, namely India, the Seychelles, east Africa, west Africa, 
South and Central America. Whether we agree With him or 
with Dr. Alcock,J who believes that the family wandered 
along a continuous land surface from India across Africa to 
northern South America in early Tertiary times, there can be 
no doubt at all as to these subterranean amphibians being 
exceedingly ancient. The American home of this circum- 
tropical family, as Dr. Gadow § points out, is South America. 
No members are known from the West Indies or the Galapagos 
* Hay, O. P., “ On Fossil Turtles,” p. 32. 
t Sarasin, F., “ Geschichte d. Tierwelt von Ceylon,” pp. 74—76. 
f Alcock, A., “ Description of Apodous Amphibian,” p. 270. 
§ Gadow, II., “ Distribution of Mexican Amphibians,” pp. 199 — 200. 
