CATALOGUE OF THE LAND AND FRESH-WATER 

 MOLLUSCA OF LOWER CALIFORNIA. 



BY J. G. COOPER. 



In an article published in the Proceedings of the California Acad- 

 emy of Sciences, second series, vol. iii, April, 1891, I stated that 

 only three species of land shells had yet been found to inhabit the 

 region on both sides of the boundary-line near lat. 32° 30', while 

 twenty-one were peculiar to the southern half of the peninsula. I 

 overlooked an incomplete list by Mr. C R. Orcutt in the " West 

 American Scientist," ii, 61, July, 1886, adding five northern species, 

 which he had traced southward to (or near) lat. 31°. They were 

 identified by Mr. Binney. He and Mr. H. Hemphill, also found 

 three new species on both sides of the line, and added much 

 to the known distribution of others. (See Binney 's 3d Supplement 

 to Terr. MoUusks, 1890, pp. 205, 219, 221 ; also the4th Suppl., 1892, 

 and the " Nautilus " for 1890-91.) 



To furnish a basis for future reference, and to point out some 

 facts needing investigation, I have compiled this catalogue of all 

 the species known from the peninsula and adjacent islands. To 

 simplify the list I omit the sub-generic names, many of which are 

 !)adly founded, thus using the nomenclature nearly as given by 

 Binney in the " Land and Fresh Water Shells of North America," 

 (Washington, 1869). 



That is the latest work giving a full account of the shells of the 

 l^eninsula, and in the twenty-one years since its issue nineteen land 

 species have been added, eleven or twelve fresh-water, and one 

 marine pulmonate species, doubling the number then known. 



Probably no other country has had so many errors made in the 

 localities given for its land-shells, and I therefore give every refer- 

 ence accessible, chiefly from Carpenter's " MoUusca of Western 

 North America," 1856 and 1864, explaining the causes of errors as 

 far as possible. 



The geographical range of each species, as far as known, is given 

 in the proper places. 



The great variability in external characters observed in all west- 

 coast land and fresh-water mollusca is strongly marked in those of 

 the peninsula, and will doubtless lead to reduction in number of 

 species. I have indicated some of these where most striking, but 



