WEST COAST PULMONATA. 499 



Santa Cruz and San Mateo Counties. 



Returning now north of Pajaro Kiver we find the Santa 

 Cruz range of mountains becoming the most prominent 

 feature of these two counties, which have verj little level 

 land throughout. They rise nearly as high as those east 

 of the bay, thus intercepting a greater portion of the moist- 

 ure from the ocean than any counties yet mentioned. Most 

 of the species of the east slope are the same as are 

 found in Santa Clara Valley, but some are only found on the 

 mountains, and though partly south of San Francisco Bay 

 are included with those "west of the ba}^" because the 

 same influence controls their distribution. This is, the 

 moister and cooler climate on the west slope, and higher 

 parts of the range, which extends to the eastern slope north 

 of Black Mt., where the peninsula also becomes cooler from 

 the water on both sides. 



Santa Cruz County especially, is more densely wooded than 

 any yet named, the redwood and fir, with some pine, hav- 

 ing once covered nearly all the west slope, with oaks and 

 other trees, chiefly evergreens, on the remaining surface, ex- 

 cept portions covered by the dense shrubbery growing on 

 steep slopes. This abundant shelter, with almost constant 

 moisture from springs, streams, and fogs, in the dry season, 

 and the additional element of abundant lime both in fossils 

 and solid strata, in some parts up to 2811 feet, make it the 

 most suitable region imaginable for land pulmonata. We 

 accordingly found that some species were very abundant 

 in local colonies where all these advantages were combined, 

 and but for the desolating effeo-ts of the terrible fires that 

 annually destroy parts of the forests, may supp )se that thej 

 would be far more abundant and generally diffused. 



The same concentration of species and of colonies at low 

 elevations continues as was before mentioned, both decreas- 

 ing in abundance with elevation, which fact may be partly 

 explained by the greater evaporation and stronger winds 



