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ORIGIN OF LIFE IN AMERICA 
chapter (p. 213), and that it might well form part of the 
indigenous fauna of the island. There are twelve species, 
some of which greatly resemble Polynesian forms, as Mr. 
Smith pointed out, and, indeed, Dr. Pilsbry has placed them 
provisionally with Endodonta, a genus otherwise confined to 
Australia and Polynesia. There are three species of Succinea, 
a genus which, seems to be particularly unfit for transport 
on drift-wood, while the most striking members of the snail- 
fauna are a species of Bulimus, seven species of Bulimulus, 
and one provisionally placed by Mr. Smith* in the South 
American genus Tomigerus. 
More recently, Dr. Pilsbry demonstrated that these 
apparently bulimoid snails are really members of the family 
Achatinidae, and that they all belong to the genus Chilonopsis. 
Since all the nearest relations of Chilonopsis are African 
genera, the affinity of this group is with Africa rather than 
with South America. But the great antiquity of Chilonopsis 
is indicated by the fact that Trichodina, to which it is closely 
allied, has a most remarkably discontinuous range, occurring 
only on some islands off the coast of West Africa and on the 
Comoro islands in East Africa. Chilonopsis, moreover, is 
more primitive than the genera of the large African Achati¬ 
nidae, and Dr. Pilsbryf expresses the opinion that it, as well 
as the related genera, originated from a common ancestor 
which lived in Mesozoic times, when Africa and South 
America were united by land. None of the species have any 
affinity with South African ones, as was supposed to be the 
case among the Hemiptera. 
Although Dr. White’s Megarhaphis has now been shown 
to belong to Macrorhaphis, a genus confined to Africa, 
two species have since been taken in west Africa. 
The supposed slight affinity of the St. Helena hugs to 
those of the Cape has therefore entirely disappeared. As 
regards the pronounced European element in the St. Helena 
insect fauna, it is probably to a large extent of American 
origin. The beetle Zophobas morio lives, outside St. Helena, 
only in west Africa, Central and South America and 
■* Smith, E. A., “ Land-shells of St. Helena,” pp. 259 — 269. 
t Pilsbry, H., “ Manual of Conchology (Pulmonata) ” (2), Yol. XVII., 
pp.171—173. 
