306 
ORIGIN OF LIFE IN AMERICA 
species of Hyalinia, a large number of Bulimuli, two Pupae, 
one Leptinaria, a Succinea and a Helicina as having been 
collected on the islands by previous visitors. He then dilates 
upon the various accidental means of transport, and concludes 
that the agency of winds and ocean currents is amply sufficient 
to explain the origin of the molluscan fauna. He acknow¬ 
ledges that the archipelago is situated within an almost wind¬ 
less area, where storms are of rare occurrence, yet maintains 
that during the course of ages the climatic features may have 
been different from those obtaining at present. He also 
emphasises the fact of the tenacity of life of mollusks and 
the length of time they are able to subsist without food, claim¬ 
ing that a theory which will fairly explain a good portion of 
the phenomena of distribution by such agencies and operating 
directly under our eyes, is preferable to those, however plau¬ 
sible and attractive, involving conjectural and remoter con¬ 
ditions. 
In his endeavour to support the theory of accidental dis¬ 
tribution as applied to the origin of the Galapagos fauna, Dr. 
Stearns seems to forget that no observation has ever been 
made clearly indicating the conveyance of mollusks or their 
eggs in drift-timber. Mollusks have never been found 
in the crevices or under the bark either of trees encountered 
on the sea or of those stranded on foreign coasts. Very 
shortly after the trees are stranded, they are no doubt invaded 
by all sorts of creatures seeking moisture and shelter; but the 
theory of accidental distribution, so ably advocated by many 
eminent naturalists still involves a good deal of the conjecture 
which Dr. Stearns is so anxious to avoid. Although Dr. 
Dali * fully acknowledges that we possess no actual proof 
in support of the drift-theory, he also concurs with Dr. 
Stearns in the opinion that there can be little doubt of the 
land snails having been introduced to the Galapagos islands 
in that manner. In his review of the molluscan fauna of the 
islands, he mentions thirty-three species of Bulimuli, two 
species of Vitrea and one of Conulus, two Pupae, four 
Succineae, one Tornatellina (Leptinaria), one Helicina and 
finally one Endodonta. Of these forty-five species, only a 
Dali, W. H., 
Insular Land-shell Faunas. 
