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. Mollusks, 1890, PP- 205, 219, 221; also the 4th 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 
badly 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 
peninsula, 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 “Mollusca 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 if number of 
‘species. I have indicated some of these where most striking, but 
