VERTIGO OF JAPAN AND EASTERN ASIA. 151 



Key to Japanese species of Vertigo. 



1. Angular lamella curving into and connected by a ridge 

 with the upper termination of the peristome (subgenus 

 Ptychalaea.) . V. dedecora, no. 41. 

 Angular lamella, if present, not connected with the upper 

 termination of the peristome (Vertigo s. sir.). 2. 



2. Having a strong palatal callus and an external crest. 3. 

 Without a palatal callus; no external crest. 6. 



3. Shell finely but sharply striate, 1.8 x 1.15 mm. ; no angu- 

 lar lamella present. V. hachijoensis, no. 36. 

 Shell smoothish, striation very weak if present. 4. 



4. An angular lamella present; basal tooth present, in a 

 subcolumellar position ; outer lip noticeably bent in near 

 the middle. 5. 

 No angular lamella ; crest very close to the lip. 



V. kushiroensis, no. 37. 



5. 2.15 x 1.4 mm. ; a suprapalatal nodule present ; crest 

 strong. V. eogea, no. 34. 

 1.75 x 1 mm. ; no suprapalatal tooth. 



V. hydrophila, no. 35. 



6. Outer lip straightened in the middle ; smoothish, aperture 

 with 4 small teeth ; 1.65 to 1.8 mm. long. 



V ". hirasei, no. 38. 

 Outer lip biarcuate. 7. 



7. Smoothish, with 1-1-2 teeth. V. japonica, no. 39. 

 Striate, with 2-1-2 teeth. V. j. tosana, no. 39&. 



Subgeuus VERTIGO s. str. 

 34. VERTIGO EOGEA n. sp. PL 14, figs. 1, 2, 3. 



The shell is rimate, broadly ovate, auburn, fading some- 

 what above, glossy, nearly smooth, but under the microscope 

 some very weak striae are seen. The whorls are moderately 

 convex, the last having a distinct, oblique impression over 

 the palatal folds, followed by a rather strong, somewhat 

 sinuous crest, which is light-colored and striate ; in the con- 

 cavity between crest and lip there is a linear impression run- 

 ning to the projection of the lip. The aperture has a well 



