66 CALIFORNIA ACADEMY OF SCIENCES. 



it is very doubtful whether it is not a mere variety. Spec- 

 imens found on this route and in other parts of Cal- 

 ifornia seem to connect them. 



20. PisiDiuM occiDENTALE Newcomb. Numerous 

 specimens so identified (and many of them compared with 

 types of the Eastern species in the National Museum) 

 were found only at the highest elevations where any mol- 

 lusca occurred, and that of 9,700 feet on the east slope 

 supplied no other species. Although first discovered 

 near the sea-level, and common down to latitude 32" in 

 the mountains east of San Diego, their place seems taken 

 on the west slope along this route by the more Eastern 

 form. Mr. Roper of Revere, Mass., who has studied 

 these difficult shells closely, and has a large collection 

 from both continents, considers this only a Western form 

 of ahdituni. 



21. PisiDiUM COMPRESSUM Prime. This very distinct 

 species was as common as the other two on the west 

 slope, but only between 8,700 and 9,000 feet in the 

 meadows near Summit. It had before been found only 

 on the east slope between about 4,000 feet at Owens' 

 River and 6,000 feet at White Pine, Nev., as well as in 

 most of the Northern States and Canada. It is reported 

 also from V^entura County and Vancouver's Island. 



22. LiMAX CAMPESTRIS OCCIDENTALIS ? J. G. CoopCr. 



I found one slug in Yosemite Valley near Mirror Lake, 

 but lost it by accident. It was small and dark-colored, 

 like the form here named, which has been found at 3,625 

 feet on the west slope and 5,866 feet on the east slope near 

 latitude 39", also at 4,000 feet in Tehachapi Pass near lat- 

 itude 35° by Dr. Cooper, as well as along the coast. It 

 is now believed by Mr. Binney and others that this inter- 

 grades toward the east with sub-species montaniis Ing. of 

 Colorado, found there up to 8,500 feet, and through that 



