WEST COAST PULMONATA. 369 



that we could miss any where they occurred. Some large 

 permanent springs also produced several fresh-water spe- 

 cies in plenty. 



The trees on this mountain are usually too scattered to 

 give much shelter, and even where most dense, no pulmo- 

 nates were found, the rock being metamorphic. 



As shown on the map, there are here two spurs of the 

 Mt. Diablo range, separated by Livermore Valley and Wal- 

 nut Creek, but farther south they join, forming the Mt. 

 Hamilton range, in which the whole country is more ele- 

 vated, many peaks being higher than Mt. Diablo, and the 

 lofty region near the southern boundary of Alameda County 

 is over 20 miles wide, sloping northwest. 



A large extent of this table land is covered with snow for 

 many weeks in winter, and large streams run from it all the 

 year into Livermore Valley. The highest parts are more or 

 less wooded with Cedars (Lib oce dries), Cypresses {Cupressus), 

 Pines and Oaks, sometimes quite densely, but being as far 

 as known metamorphic, no land mollusca have been found 

 high up. The northwest summer winds seem to condense 

 the fogs from the sea upon these high regions, while they 

 cool the air without so much desiccation as on the lower 

 ridges and valleys. But unlike the Sierra Nevada, this range 

 does not seem to produce land pulmonates above 1,000 feet, 

 and as on Mount Diablo they only occur near fossils. Dr. 

 Yates explored much of the region, and not having been 

 there myself, I quote from his letters: " I only found land 

 shells where the miocene or cretaceous fossiliferous sand- 

 stones cropped out, between 800 and 1,100 feet elevation, six 

 miles N. W. of the summit of Cedar Mountain. These 

 rocks in the deep ravines along the west side of the ridge 

 near its base, contain many fossils; higher up, it is all 

 metamorphic and no land shells were found." The species 

 he found were 7, 15, 30, 34, 37. 



Thus the general fact is confirmed that No. 37 is one of 

 the group living in or near coniferous forests where the soil 



26-BuLL. Cal. Acad. Sci. II. 7. Issued May 25, 1887. 



