410 
ORIGIN OP LIFE £N AMERICA 
(p. 120) that the mammals inhabiting Patagonia and south¬ 
western North America in late Mesozoic and early Tertiary 
times indicated the existence of a direct land bridge between 
these two areas. But the Patagonian land-mass must have 
included Chile or such parts of it as were then above sea- 
level. We know very little of the past fauna of Chile. If, 
as I endeavour to prove, a portion of our living fauna is of 
great antiquity, some animals should reveal unmistakable 
signs of this early affinity of Chile with that of south-western 
North America. I imagine, as previously stated, that the early 
Tertiary land bridge connected Chile directly with western 
Mexico and California. Hence we might expect that not only 
Chile and Patagonia, but the outlying islands of California, 
as well as the Galapagos islands, ought to show a faunistic 
relationship with one another. 
I have already alluded to the fact that three groups of the 
snail Bulimulus inhabiting Chile and Peru, the Galapagos 
islands and Lower California are very similar in their narrow 
elongated shape, so that they were formerly considered to be 
very closely related. Dr. Pilsbry* is now of opinion that this 
similarity in appearance is not any evidence of near relation¬ 
ship but a special parallel modification of different Bulimulus 
stocks, or, as we might say, a case of convergence. He attri¬ 
butes these cases to be products of similar environments. Yet 
is the environment of Chile really so similar to that of the 
Galapagos islands or Lower California ? Climatically and geo¬ 
logically I should think there must be a good deal of difference 
between these districts. 
The relationship between the western North American snail 
fauna and that of western and south western South America 
is well illustrated by the distribution of the genus Epi- 
phragmophora. This is a group of snails entirely confined to 
Central America and the Pacific borders of North and South 
America. It is important to note also that the majority of 
the snails inhabiting the islands off the coast of California 
belong to this genus. Cerros, Guadelupe, Santa Barbara, 
San Clemente and other islands all have their peculiar species 
of Epiphragmophora. Now the most interesting point about 
* Pilsbry, II. A., “Manual of Conchology (Pulmonata),” X., p. 126. 
