654 



STEARNS 



E. fidelis exhibits very considerable variation in color and form. 

 Some of the color varieties are quite shovs^y, surpassing in this respect 

 all other American Helices. This feature, however, need not be con- 

 sidered in connection with fossil examples. Variation in form and 

 size has a more important bearing as will be seen by the following. 

 Carinate, subcarinate, and dwarfed forms have been observed by va- 

 rious authors ; these varietal aspects appear to be closely related to 

 physiographic influences. The dwarfing which is seen in the speci- 

 mens from the region of the Dalles of the Columbia River, and from 

 Shasta County, California, indicate diminution in size as related to 

 easterly distribution, while the tendency to angulation of the whorls 

 seems to be coincident with distribution toward the south as exhibited 

 in E. Jidelis infumata of the Coast region as far south as Marin county, 

 California, or nearly to the Bay of San Francisco. E. Jidelis sub- 

 carinata of the Humboldt County forested region, is an intermediate 

 and connecting link hetw&Qn Jidelis proper, and the infumata aspect, 

 not only in form but geographically also. It may be worth mention- 

 ing that the Jidelis forms, unlike the other characteristic banded or 

 markedly colored ^ West Coast snails, become darker^ or shade con- 

 spicuously into jnelanism in their southerly distribution. 



E. jnormonum, which may be regarded in a general way as a higher 

 mountain form, ranges from Shasta County to Tulare. Its zone of 

 distribution is along the westerly slopes of the Sierra Nevada; it is, in 

 my opinion, the hypsometric and easterly expression of the Jidelis 

 stock, the easterly and higher altitude branch of that form, extending 

 to the south ; it is said to approach the coast in Santa Barbara County, 

 but how near to the sea, or at what altitude it has been detected in that 

 direction, I do not know. The deflection of the Sierra Nevada range 

 toward the southwest and the merging of its westerly flanks into the 

 easterly outlying elevation of the coast ranges in this part of the State 

 would furnish a highway for migration, as may be seen by a glance at 

 the map. Binney^ has shown that in its anatomical characters, the 

 animal is quite different from the other Ariontcs (= Epiphragmo- 

 phoras), and more Wke Jidelis a.ni\ Jidelis-infti77tata. 



Fossilized shells of mor^nonuin could not readily be separated from 

 similar specimens of Jidelis of the same size. The average size of 

 mormonum is much less than the average of typical Jidelis^ approxl- 



> That is to say, high colored when compared with the horn-colored eastern 

 shells, and town send iana, columbiana, etc., of the West Coast. 



2W. G. Binney, Manual of American I,and Shells; Bull. 28 U. S. Nat. Mu- 

 seum, pp. 121-123, 140, 141. 



