44 BULLETIN OF THE 



Microphysa conspectt . Bi., 

 See p. 35, 



Microphysa Stearnsi, Bl. 



See Supplement I. p. 147. Found also in iUaska. 



Helicodiscus lineatus, Say. 

 Vallonia pulchella, Mull. 

 San Diego, California. 



Gonostoma Yatesi, J. G. Coop. 

 Polygyra Harfordiana, J. G. Coop 

 TrioHopsis loricata, Gld. 

 Stenotrema germanum, Gld. 



Mesodon Columbianus, Lea. 



The true M. Columbianus is correctly described and figured in Terr. Moll,. II. 

 and III. It is very readily distinguished by its peristome, the basal margin of 

 which is horizontal in its direction, with a slight thickening or projection before 

 it reaches the base of the shell. It does not appear to range as far southerly as 

 California. Northerly it has been found to 59° latitude. 



The form called labiosa by Dr. Gould (see Vol. II.) is recognized by its very 

 circular aperture, its widely reflected, sinuous peristome, sharp on its outer edge, 

 not flattened on its face. Its ujiper surface is elevated as in Columbianus. It is 

 sometimes toothed. Originally found iii the region of Astoria, Mr. Hemphill 

 has collected it at Kalama on the Columbia River, forty miles below Portland, 

 a|nd also from Deer Lodge Valley, Montana, and in the Coeur d'Alene Moun- 

 tains, Idaho. (See p. 39.) 



My Figs. 4, 5 of Plate I. show the toothed variety from Idaho and an enlarged 

 view of the epidermis. It is less hirsute than armigerus. 



The form called armigerus by Aiicey (Le Naturaliste) is the one common in 

 California, ranging as far south as 37° 20'. I have figured it on PI. I. Fig. 12, 

 as well as an enlarged view of the epidermis. It is the most densely hirsute of 

 the group. It is a more globo.?e shell below than the typical form. The peris- 

 tome is narrow, much less develojjcd ; the 'parietal tooth is long and narrow, 

 sometimes wanting. It has much the appearance below of a large Stenotrema 

 germanum, with which species I have confounded it rather than with Colum- 

 bianus. I have no doubt it will eventually be considered a distinct species. 



Mesodon devius, Gld. 



As restricted (see p. 36), this species seems to be confined to the Oregon 



Aglaja fidelis, Gray. Aglaja Hillebrandi, Newc. 



infumata Gld. ArioD'--a arrosa, Gld. 



