ADDITIONS AND CORRECTIONS. 373> 



tremes, however, are fully connected in the Bluff Lake series, 

 which must thus be treated as a unit. As in the Santa Cata- 

 lina race of this species (p. 132), albino shells occur in some 

 abundance. As in many other cases, the albino mutation 

 occurs in colonies with the brown shells, and there is no 

 reason to believe that it does not interbreed with them, as has 

 been demonstrated for a number of other such cases. Dr. 

 Berry has described the albino mutation as V. m. micro- 

 phasma. In the writer's opinion the brown shells found with 

 them are of the same race ; but the name can be used for the 

 San Bernardino race as a whole, with its several variations 

 and mutations. Though certainly without definite differen- 

 tial characters, it is not, as a whole, either typical castanea or 

 typical parietalis. 



VERTIGO MODESTA MICROPHASMA Berry. Figs. 1-6. 



"The shell is cylindro-conic, rimate-umbilicate, thin, very 

 pale horn-color, by transmitted light transparent and color- 

 less. The surface is glossy and distinctly, irregularly, ob- 

 liquely striate, especially on the upper whorls. The spire 

 tapers from the last whorl, at first gradually, then more 

 rapidly, to the obtuse apex. The whorls are strongly convex, 

 the last with an indentation just back of the aperture over 

 the lower palatal tooth, subsequently with a narrow, abrupt, 

 axial constriction, then swollen to form a low, wave-like crest 

 just back of and parallel to the lip. The aperture is rounded 

 triangular, scarcely constricted on the outer margin, the peri- 

 stome thickened and porcelain white in color, showing through 

 the back of the shell as a white line, but the sharp lip scarcely 

 reflected except over the columella. The posterior angle of 

 the outer lip curves in rather sharply to the body whorl. The 

 number of teeth varies from 2 to 5. The parietal and colu- 

 mellar lamellae are always well developed. In addition there 

 is almost always a well-developed lower palatal. A smaller, 

 but variable upper palatal is frequently present, as also a 

 minute angular lamella. All the teeth are porcelain-white in 

 color. 



