WEST COAST PULMONATA. 375 



are found up to 1,000 feet elevation rarely. No. 36 is not 

 found south of Alameda Creek, and No. 32 becomes the 

 prevailing form of 30, as it was in the dry region near Mt. 

 Diablo. 



The species of the upper part of Alameda Creek basin 

 liaving been mentioned, there only remaki about 200 square 

 miles of Alameda County around Mission Peak. The only 

 species known from there are Nos. 24 and 32; but close 

 search will probably reveal other smaller species. There 

 is, however, an evidently rapid decrease, caused chiefly by 

 dryness. Dr. Yates thinks that No. 32 goes higher up 

 this peak than elsewhere, fossils being also found nearly to 

 its summit, where a less arid climate must prevail. 



From here southeast the Mt. Hamilton range has been 

 mentioned as not known to produce any species on the 

 liigher portions. But some of the lower ranges on its west 

 slope are fossiliferous, and may be supposed to have some 

 species, especially Nos. 5,8, 9, 14, 32, 37, the best suited for 

 dry regions, and in wet places, Nos. 42 to 45. Though part 

 of the same mountain range described last, it belongs to the 

 next county to be mentioned. 



On the map the number 686 is the height in feet of Liver- 

 more Pass (a little west of the figures), 485 is the elevation 

 of the town of Livermore, 264 of Suiiol, at the head of 

 Alameda canon, the lagoon referred to being a few feet 

 higher and some five miles northward. The lettering often 

 obscures the lines of elevation, so that they cannot always 

 be counted for heights. 



The next article will describe the distribution in the re- 

 maining counties, and give the geological deductions de- 

 rived therefrom, showing why it differs so much from that 

 of the Sierra Nevada. 



