04 THE NAUTILUS. 



MOLLUSKS COLLECTED BY R. C. McGREGOR IN NORTHERN 

 CALIFORNIA. 



BY HENRY A. PILSBRY. 



Mr. R. C. McGregor being engaged during the summer of 1898 

 in Fish Commission work which took him over a considerable area 

 in northern California, interested himself in the collection of mol- 

 lusks, which he sent me for study. 



The region is one which has been very superficially examined 

 hitherto, and it is not surprising that a number of very interesting 

 species were found. But few land shell's were taken, among them 

 the extremely rare Polygyra roperi, and a peculiar Circinaria. 

 Pyramidula striatella occurred in many localities, the specimens be- 

 ing referable, probably, to the ill-defined variety cronkhitei. 



Among the fresh-water pulmonates, the re-discovery of Ancylns 

 patelloides Lea, a species falling into Clessin's genus Lanx, and A. 

 alius Tryon, also a Lanx, are the most important finds. These 

 species will be fully treated elsewhere, with illustrations of the 

 anatomy. 



The series of Goniobases collected induced me to attempt a revision 

 of the West American species, the results of which are included below. 



The list of species is as follows : 



Epiphragmophora mormonum (Pfr.). Redding, Shasta Co. 



Polygyra loricata (Gld.). Battle Creek, s. boundary Shasta Co. 



Polygyra roperi (Pils.). Redding, Shasta Co. One adult specimen. 



Vallonia pulchella (Mull.). Redding, Shasta Co. 



Circinaria sp. undet. Redding. I cannot refer the single fresh 

 adult shell collected to any of the described forms. 



Pyramidula striatella (Anth.). Goose Lake, Modoc Co.; Duck 

 Lake, 20 miles west of Susanville, and Eagle Lake, Lassen Co.; 

 Bartle's, Siskiyou Co., on McCloud River. 



Vitrea hammonis (Strom). Bartle's and Duck Lake. 



Vitrina pfeifferi Newc. Bartle's and Duck Lake. 



Zonitoides arboreus (Say). Goose Lake, Modoc Co. 



Succinea nuttalliana (Lea). Goose Lake, Modoc Co. 



Snccinea stretchiana (Bid.). Duck Lake and Bartle's. 



Limncea stagnalis (L.). Upper waters of Willow Creek, trib. to 

 Susan R., Lassen Co. 



Limncea proxima (Lea). South Fork Pitt R., Modoc Co. 



