I 



From the Proceedings of the California Academy of Sciences, February 1st, 1875. 



The Origin of Culiforniaii Land-Shells. 



BY J. a. COOPEE, M. D. 



In previous articles I have giveii some observations on the Distribution and 

 Variations of the Califoruian Banded Land-shells, which naturally lead to the 

 consideration of their probable origin or past history. 



In the "Bulletin of the Museum of Comparative Zoology," (Cambridge, 

 Mass., June, 1873, p. 202), Mr. W. G. Binn.-y writes, "the west alone is left 

 to us from whence to trace the Pnlmonate Fauna of the Pacific region, and 

 there the secret of its origin lies buried imder the Pacific Ocean." 



Mr. Binney probably alluded to the supjiosed existence of a continent 

 ju the South Pacific, embracing the mountain summits now forming the 

 archipelago of Oceania, which became submerged, as Prof. Dana suggests, 

 during the later tertiary period, while most of California was emerging from 

 the ocean. ; 



But even if this were proved to have happened, the great distance of the 

 nearest islands (the Hawaiian) from iis, and the great depth of the ocean 

 between, as well as north of them, besides the total dissimilarity of thtir 

 living laud-shells from ours, forbids any supposition ot a former land connec- 

 tion by which such animals could travel directly from one country to the other. 

 A glance at a globe shows that the islands, besides being tropical and wholly 

 south of lat. 23*^, are as far from us as the Aleutian Islands, the Arctic Ocean, 

 or i'lorida, and I propose to show that whatever migration to California has 

 occurred, came from the dii'ection of the regions named last. 



No confirmation is given to a derivation from the west, by the more probable 

 former existence of an "Atlantis" connecting the two continents across the 

 Atlantic, the few island remnants of which really contain several species of 

 land-shells common to one or both sides. 



The great similarity of our banded groups to those of Europe has always 

 been an argument for sui^posing them to have had a common origin. The 

 same similarity is found in many others of our animals as well as plants, and 

 is plainly connected with the well-known similaritj' of climates in the two 

 countries. But as the known laws of nature do not jjermit us to consider 

 climate as the cause of specific resemblances, we mu>t look for some other 

 way of accounting for them in this case. 



The fact that very similar species exist in Japan and the Amoor Valley, 

 Siberia, contradicts, indeed, the theory of climatic causes, since we know that 

 the climate of those regions is very similar to that of our Atlantic States 

 where no similar species exist. At the same time, their existence there sug- 

 gests the probable central point from which all originated. 



Going back in geological history to the sup^josed beginning of all living 

 species, few; if any, of the terrestrial, can be traced farther back than the 



