ADDITIONS AND CORRECTIONS. 375 



and S. S. Berry, August, 1910 ; 59 specimens in this and 

 neighboring cienagas. Also taken at 7,200 feet altitude, west, 

 slope of Falls Creek Canyon, near the narrows about one 

 mile above Dobbs Cabin, Dollar Pass Trail, San Bernardino 

 Mountains, California ; under small sticks and pine cones on 

 springy slope ; G. E. Dole and S. 8. Berry, Sept. 29, 1918 ; 

 32 specimens" (Berry}. 



Vertigo modesta microphasma BERRY, Nautilus, xxxiii, Oct. 

 1919, p. 48, figs. 1-6. 



' ' This very puzzling little mollusk is one of the most beau- 

 tiful of American Vertigos. It is very close to V. modesta 

 parietalis and may also be described as an albinistic race of 

 that subspecies, but it is a protean form and some shells are 

 equally close to V. modesta modesta or even to V. m. castanea. 

 That it is more than a mere 'albino' of the recognized type 

 is strongly evidenced by its occurrence in such abundance and 

 at scattered localities, as also by the fact that its distribution 

 is by no means coincident with that of any of the other forms 

 mentioned. Nor, although usually associated, do the white or 

 brown shells occur in any apparent regular ratio. At the 

 second locality above cited diligent outlook yielded but three 

 specimens of the brown parietalis. It is evidently a com- 

 paratively recent offshoot from the parent stock, but the field 

 evidence is that it already is a race with its peculiar char- 

 acters heritable to a marked degree. 



' ' It seems rather remarkable that such features as the color, 

 shell texture, and similar characters in this form should ex- 

 hibit such constancy as compared with the variability shown 

 in the development of the lamellae. In 39 specimens of the 

 type lot now before me, 1 has only 2 teeth (columellar and 

 parietal), 15 have 3 teeth (columellar, parietal, and lower 

 palatal), 9 have 4 teeth (an upper palatal usually the one 

 added), and 14 have a full set of 5 teeth. No mature speci- 

 mens with fewer than 2 nor more than 5 teeth have been 

 noted. This variation in a single well-defined colony (its 

 members having, as shown by the other characters noted, an 

 undoubtedly close phylogenetic relationship with one an- 

 other) throws a valuable bit of light on the difficulty of at- 



