6 SMITHSONIA>J MISCELLANEOUS COLLECTIONS VOL. 92 



vex whorls, and smaller subovate aperture and very gently curved 

 columella ; while bolotensis has a shorter spire with fat whorls, and 

 shallower suturr. 



LYMNAEA (RADIX) ZAZURNENSIS, n. sp. 



Plate I, fig. 2 



Shell of fairly large size, length 18.5 mm, broad relative to the 

 length, horn-colored ; surface bright, glossy, crossed by many regularly 

 spaced lines of growth which give the shell a slightly ribbed appear- 

 ance, and by many microscopic spiral impressed lines ; whorls five, con- 

 vex, protruding and well rounded in all cases ; the body whorl nearly 

 semicircular in outline on the left side; having a slightly shouldered 

 appearance at the junction with the preceding whcjrl, Init actually 

 having a small V-shaped depression intervening and continuing around 

 the shell for at least one whorl above the aperture ; aperture ovate- 

 ellipsoidal ; outer lip thin, sharp ; inner lip gradually curving, colu- 

 mella nearly flat, not twisted, spreading out to some extent over the 

 umbilical region, which is seen from the side and below to be fairly 

 wide open. 



Type. — U.S.N.M. no. 470709, collected at Lake Zazurnia, in the 

 mountain range known as Khamar Daban, eastern shore of Lake 

 Baikal. The species is known only from the type locality. 



Measurements oj the Shells of Lymnaea zaziirncnsis fro 

 Khamar Daban, Siberia 



Type 



PLANORBIS (SPIRALINA) JOHANSENI, n. sp. 



Plate I, fig. 8 



Shell of moderate size, greater diameter 7.5 mm, discoidal, very thin 

 (height 1.2 mm) slightly concave above and below, closely resembling 

 P. coriiprcssus; surface bright and shining, with many fine but distinct 



