348 
ORIGIN OF LIFE IN AMERICA 
Ecuador (compare Fig. 14). As this western belt of land 
was in direct communication with the West Indies by way 
of Central America, it follows that the West Indies and 
Ecuador were able to enter into a faunistic exchange. Many 
instances might be quoted showing this relationship between 
the West Indies, Central America and western South 
America, or between parts of these areas. The head¬ 
quarters of the snake-like limbless amphibians, known as 
Coecilia, are in Ecuador. From there they have spread 
eastward through Guiana to Brazil, and northward through 
Colombia as far as Panama. No species is actually known 
to occur in Central America beyond Panama. I alluded 
to the family Anguidae on several occasions, those generally 
limbless lizards to which the so-called glass-snake belongs. 
One genus with well-developed limbs (Diploglossus), inhabits 
chiefly the principal islands of the West Indies, viz., Cuba, 
Haiti and Jamaica. In Central America it occurs in Guate¬ 
mala and Costa Rica, while in South America it inhabits only 
Ecuador and Brazil, having apparently spread into the latter 
state from the west. 
Attention has been drawn to the fact that while the fauna 
and flora of the Galapagos islands are principally Central 
American and West Indian in character, they also are related 
to those of western South America. A mere fragment only 
of the animals and plants that passed across the lands of 
which these islands formed part could have been preserved 
there. Thus the Streptaxidae, a family of carnivorous snails 
almost restricted in America to the southern continent, do 
not occur in the Galapagos islands, although a few species 
have penetrated to Guatemala, and one even to Haiti. The 
genus Martinella is peculiar to Ecuador, whereas two other 
genera, viz., Guestieria and Systrophia appear to have spread 
from an Ecuadorian centre of dispersal to Peru, Colombia 
and Bolivia. 
A most interesting and important case of discontinuous dis¬ 
tribution is that of Clausilia, a genus of snails which I men¬ 
tioned when dealing with the origin of the West Indian fauna 
(p. 27*2). I then stated the reasons for my belief that 
Clausilia had travelled across the mid-Atlantic land bridge 
from southern Europe to the West Indies rather than by a 
