THE NAUTILUS. 123 



closed and the shell more compact ; it is very close to facta.'' 

 " Doubtless all are branches of one stem." 



It will be seen by Dr. Dall's remarks that our shell stands closely 

 related to his catcdince and guadalupiana, with very great differences 

 in size, besides those he has pointed out, which entitle our shell to a 

 name as a variety. As they are " doubtless all branches of one 

 stem," and as we have the stem in Helix ruficincta Newc., let us be 

 consistent, follow nature, and call all of them branches (varieties) 

 and not distinct stems. 



Helix Tryonii major Hemph. 



This variety is very much larger than any of the very many 

 specimens that I have collected. One of the specimens is globosely 

 depressed, with an effuse subcircular aperture and a prominent 

 tubercle on the basal portion of the peristome near the termination 

 of the columella. The peristome is thickened, not reflected, the 

 ends not approaching, but they are joined by a heavy callus. The 

 other specimen is narrower, with a conical elevated spire ; the aper- 

 ture is very oblique, laterally expanded, and wider than it is high ; 

 the peristome is greatly thickened near the columella, but without a 

 tubercle, not reflected ; the ends are very much approached, no per- 

 ceptible callus joining them. 



Diam. 30, alt. 23 mm.; diam. 27, alt, 26 mm. 



Habitat : San Nicolas Island, Cal.; subfossil. 



Helix Tryonii minor Hemph. 



The shell is very much smaller than the types, and shows about 

 the same differences in the elevation and depression of the spire and 

 in the form of the aperture as var. major. There is no tubercle on 

 the basal lip, which is very little thickened. 



Diam. 17, alt. 13 mm.; diam. 16^, alt. 13^ mm. 



Habitat : San Nicolas Island, Cal.; subfossil. 



This small form is very close to Helix vnr.feralis. 



Helix Tryonii maculata n. color- var. 



Ground color ashy white, lighter beneath than above ; the body 

 whorl and spire speckled with darker spots, banded or bandless at 

 the periphery, form variable in size ; spire elevated or depressed. 



Diam. 25, alt. 19 mm.; diam. 20, alt. 16^ mm.; diam. 22, alt. 

 15 mm. 



Habitat : Santa Barbara Island, Cal. 



