186 PROCEEDINGS OF THE CALIFORNIA 
Helix Veatchii from Cerros or Cedros Island, off the coast on the ocean side 
of the same, come from within the same physical environment, being com- 
paratively a limited distance apart. 
The Helix belongs to an interesting and peculiar group, probably varieties 
of one species, which includes, at present, the following names: (1) Helix areo- 
lata, Sby., (2) H. Veitchit, Newc., (3) H. pandore, Fbs., and (4) H. levis, Pfr. 
Other forms geographically approximate may hereafter, on further investiga- 
tion, be referred to the same lineage. 
Of the above, (1) H. areolata was the first described, or I should say that this 
appears by the date to be the first name bestowed upon any member of the 
group. This species has been quoted from Oregon, and (4) H. levis, from the 
Columbia River, in both cases erroneously. The figures in ‘‘ Land and Fresh 
Water Shells of North America,’’* p. 177, are too elevated and globose for 
the typical areolata, but the larger figures faithfully represent H. Veatchit. 
Elevation and rotundity are insular characteristics in this group, and areolata 
is comparatively depressed. It is found in considerable numbers on the up- 
lands around Magdalena Bay, which is on the outer or ocean shore of the 
peninsula, in latitude about 24° 40’ N. 
Bulimus pallidior, which is pretty generally distributed through Lower Cali- 
fornia, from Cape St. Lucas northerly, has also erroneously been credited to 
San Diego in California proper. It is arboreal in its habits, at least during 
the winter season, and frequents the Copaiva trees. It has been said to in- 
habit South America, which is probably incorrect, and the locality ‘‘San Juan,’’ 
mentioned in ‘‘L. and F. W. Shells,’’ on p. 195, where a good figure of this 
species may be seen, should be San Juanico, which is on the east side of the 
peninsula, in latitude about 27° N. 
The great importance of particularity in habitat will be at once perceived 
when I state that there are no less than three other localities on the west coast 
of America, north of the place cited, all of which are referred to in various 
scientific works which have come under my observation, as ‘‘ San Juan,’’ and 
there are perhaps as many more ‘‘ San Juan’s”’ south of that especially quoted 
herein, on the westerly coast of America, in the Central and South American 
States. 
Attention is directed to the fact that the three species herein mentioned as 
exhibiting extraordinary vitality, belong to geographical areas, which receive 
only minimum rainfall, or which are, in simple language, nearly rainless 
regions. 
Within such areas vegetation is exceedingly limited even in favorable sea- 
sons, and the presence and growth of the annual plants is, of course, depend- 
ent upon the rainfall; this last occurring infrequently makes the food supply 
of land mollusks and other phytophagous or vegetable-eating animals exceed- 
ingly precarious. | 
It is highly probable that a careful investigation in this direction will lead 
us to the conclusion that the land mollusks which inhabit arid areas have, 
through selection, adaptation and evolution, become especially fitted for the 
*Smithsonian Misc. Coll., No. 194. 
