366 CALIFORNIA ACADEMY OF SCIENCES. 



Joaquin River from near its head in lat. 37*^, that 

 wonkl not have carried it north of San Francisco 

 Bay, and it is known up to lat. 39^ on the east 

 slope of the Coast Eange, while none like it oc- 

 cur near branches of the Sacramento Eiver eastward. 

 From this I argue that it has either spread from the 

 Coast Range east, or that the forms of each range were de- 

 rived by changes caused by climate, etc., from the Oregon 

 shells of the same group.. More numerous comparisons and 

 dissections of connecting links will be required to decide 

 on the true limits of the species and sub-species. 



In the region between Monterey and lat. 35^ there are no 

 traces of any forms connecting the only Sierra Arionta 

 (tucUcidata) with those nearest allied to it, which all exist 

 within the limits of the Bay region here given. The same 

 objection applies to the theory of their derivation from 

 shells washed down from the Sierras, as in the previous 

 case, especially as they are known along the coast up 

 to lat. 41° at least. (See article on the law of Variation 

 in the Banded Helices, in Proc. Cal. Acad. VI, 121, 1873.) 



The names of localities given on the map are referred to 

 in this article, or in former papers, and to prevent confus- 

 ion names of towns are omitted, but their locations being 

 marked, they can be easil}^ recognized. The essential out- 

 lines are nearly correct, except the position of Mt. St. 

 Helena, the summit of which is nine miles north of the 

 limit of the map, and being in the volcanic region is only 

 given to show the increase of elevation in the country 

 toward the north, as the size of the pages would not adaiit 

 of including any more of the map in tJiat direction, nor 

 was it needed to illustrate the text. The heights given with 

 exact number of feet are accurate; others, as 300, 2,600, 

 etc., are only approximate. 



