AMERICAN SPECIES OP VERTIGO. 133 



without description. It was first described and figured from 

 Fresno Co. specimens, the type being no. 11655 A. N. S. P. 

 (pi. 10, fig. 6). 



The typical form has three teeth, parietal, columellar and 

 lower palatal; but there are also specimens in the same lot 

 which lack the palatal, and one without any teeth. 



In a lot from Wood 's creek, Tulare Co., there are specimens 

 having 3 teeth, 4 teeth (a minute angular lamella being 

 added), and no teeth (page 124, fig. 9<z), though the shells 

 seem otherwise to be equally mature. As the teeth appear 

 before the lip is fully formed, this variation is clearly not a 

 matter of age. 



A very minute but distinct upper palatal fold is seen in 

 some specimens, as no. 115204, from mouth of big arroyo, Kern 

 Eiver, Tulare Co. (page 124, fig. 9). Others of the same lot 

 have three teeth, and in others a minute angular lamella is 

 developed also. The teeth are best developed in specimens 

 from Eae Lake (pi. 10, fig. 5), some of which would be re- 

 ferred to parietalis were they not associated with others more 

 or less deficient in teeth, or without teeth, but otherwise 

 similar. In this lot the shell is largely whitish, or is streaked 

 with white. 



Some lots contain among normally proportioned shells, a 

 few short examples such as page 124, fig. 9&, but having the 

 crest and lip of adult character. Two from Onion valley, 

 Kearsarge Pass measure: 



Length 2.5, diam. 1.4 mm. (normal). 



Length 2.3, diam. 1.5 mm. (page 124, fig. 9&). 



The more cylindric shape and the distinct crest behind the 

 lip distinguish this race from V. occidentalis. I have not 

 seen specimens from Lake Co., but the other localities are well 

 represented in the collection of the Academy. 



V. m. easterner in some of its forms, does not seem distin- 

 guishable from V. arctica and V. m. ultima so far as I can see ; 

 yet as it has some different mutations, the localities are re- 

 mote, and none have been found in the intervening territory, 

 it may belong to an independent, parallel line of differentiation 

 of the modesta-parietalis stock. On the other hand, there may 



