92 PROCEEDINGS OF THE CALIFORNIA 



Dr. Carl Von Scherzer, Chief Commissioner of the Commercial 

 and Scientific Embassy from the Austrian Government to Eastern 

 Asia and America, was invited to address the Society, and gave an 

 interesting account of his observations in China. 



Dr. Cooper presented the following : 



The West-Coast Presh-water Univalves, No. 1. 



BY J. G. COOPER, M.D. 



In the " Geographical Catalogue of West-Coast Mollusca," published 1867, 

 I gave the names and range of the species known at that time ; but having col- 

 lected comparatively little in the interior, and being unable to obtain from East- 

 ern conchologists a named series of even those I had collected, I compiled the 

 list from the most recent publications of the work of others. Since that time, 

 by the accumulation of new materials, Ihat catalogue has already become anti- 

 quated, and I now propose to give some results of these later collections, made 

 partly by me, but chiefly by my friends. Rev. J. Rowell, H. P. Carlton, G. W. 

 Dunn, L. G. Yates, H. N. Bolander, Dr. C. A. Canfield, W. G. W. Harford, 

 AV. H. Holder, C. D. Voy, and the late J. Hepburn. To the two first named 

 gentlemen I am especially indebted for typical specimens of the new forms dis- 

 covered by them, and lately described by Tryon and Lea. 



The Academy's Museum has also supplied types of several species discovered 



by Dr. J. B. Trask, Dr. J. A. Veatch, and the late Dr. A. Randall, some of 



*them but lately described from the collections of Mr. W. M. Gabb and Dr. W. 



Newcomb, who obtained many from the same sources. (See also, Dall, in 



Vol. in, p. 264, on subfam. Pompholina, etc.) 



Geographical Distribution. 



The geographical distribution of fresh-water shells is very different usually 

 from that of the terrestrial or marine species, and differs among themselves very 

 much according to the family to which they belong. One generalization may 

 be safely made, viz : that the Pulmonate species have often a vast range, while 

 those able to live but a short time out of water are confined to comparatively 

 marrow limits, each stream or lake often having its species nearly or quite pecu- 

 liar. Local variations are also common among the Pulmouates, but not so 

 strongly defined, nor usually admitting the rank of species. 



Thus, among 20 Limneids given in the Geog. Cat., the first, L. stagnalis, is 

 fuadoubtediy circumpolar in range, those of the two continents beiqg undistiu- 

 rguishable. The third, L. elodes Say., ( palustris Linn. ?) is considered by many 

 .•authors identical with the European form, but seems to me as well entitled to 

 specific rank as many others. This we have in common with the Atlantic 

 slope, but we also have several local varieties, at first called species, e. g., prox- 

 dma Lea, Traskii Tryon, and perhaps others. * 



The other Pulmonates are, however, ail peculiar to North America, an^ even 

 to this west slope, in the opinion of several recent authors. 



