THE NAUTILUS. 101 



ruination. It will be noticed, they are all common fresh-water 

 species. The first lot includes Planorbis parvus, P. campanulatus, 

 Limncea luntiilis, Pltysa heterostropha, Valvata carinata and V. sin- 

 cera ; all of the above Say's species. The foregoing are from the 

 " fossiliferous sands overlying the clays of Essex county," Ontario, 

 Canada ("Pleistocene "), and are associated with Mastodon remains. 



They were collected in 18 ( J7 by Dr. Henry M. Ami, of the Can- 

 adian Geological Survey, and sent to Dr. Edwards by the collector, 

 presumably with microscopic material. 



In the second lot, there is only the single species Planorbis parvus 

 Say; this was found associated with Mastodon remains at Newlrjrgh, 

 N. Y., by F. W. Schaffer (in 1899), who sent the examples to Dr. 

 Edwards. Of the species named herein, P. pan-us and L. humilis 

 exhibit a wide distribution in the past as well as in the present times. 

 Both of these are reported as occurring living, and fossil, in the 

 Lahontan and Bonneville areas of the Great Basin ; P. heterostropha, 

 living in both, but semi-fossil only in Bonneville. V. sincera credited 

 to Salt Lake, living, by its collector Henry Ilemphill, is represented 

 as a semi-fossil in the Bonneville area by Call's var. Utahensis. The 

 occurrence of living examples in either of the areas mentioned, 

 is not noted in Call's list of Great Basin mollusca. 1 While, L. lium- 

 ilis is everywhere, east and west, north, and pretty widely dispersed 

 towards the south, P. c<inip<titnl<if><s has a much more restricted 

 range and has yet to be reported west of the Rocky Mountains. 



I have to thank Mr. C. W. Johnson of the Wagner Free Institute 

 for kind attention connected with the above. 



ROUT. E. C. STEARNS. 

 Los Angeles, Gal., October, 1890. 



DREDGING IN SAN DIEGO BAY. 



BY F. AV. KELSEY. 



The use of the dredge has afforded me a great deal of pleasure, 

 while furnishing me with a goodly amount of wholesome physical 

 exercise so much needed by those following sedentary occupations, 

 and the specimens thus obtained add largely to my local collection. 



While working in the bay I use a dredge cutting but 14 inches, 



1 Bulletin No. 11., U. S. Geographical Survey. 



