42 STROBILOPS OF JiVPAN, KOREA AND CHINA. 



Endodonta helleri D.vll, Proc. A. N. S. Phila., 1900, p. 94, 

 pi. 8, figs. 7, 8, 9. 



The low contour, the acute, margined keel, the wide um- 

 bilicus and deeply immersed iufraparietal lamella, as well as 

 the small number of whorls, strongly characterize this species. 

 It appears to be most like the Central American S. salvini, 

 which however has more numerous whorls. 



As 8. helleri is known by only one specimen (no. 108515 U. 

 S. N. M.), I have not examined the interior. Only two basal 

 plicae are visible through the shell, wliich is rather thick; 

 probably there are three, in addition to a columellar lamella. 

 The last two whorls are somewhat more convex above than the 

 draughtsman has represented them in fig. 3. 



Section Eostrobilops, n. sect. 



Gruppe der StroMlops diptyx Wenz, Neues Jahrb. Min., 

 Geol. u. Pal., 1915, II, p. 84. 



The shell is convexly conic, finely striate, with a rather 

 small umbilicus. The parietal and iufraparietal lamellae 

 emerge, and deep within their edges have prickly or rugose 

 knots or nodes (and in recent species flare outward) ; there is 

 no interparietal lamella. Internal barrier consisting of a low 

 columellar and two to four basal folds, sometimes also a palatal 

 fold. Type S. hirasei. 



All known species of Japan, Korea and China belong to this 

 group. Some of the European Tertiary species are more de- 

 pressed than Recent forms. 



Key to Species of Japan, Korea and China. 



1. Larger species, diam. 3 to 3.5 mm.; umbilicus contained 



about 5% to 7I/2 times in diameter of the shell (2). 

 Smaller species, diam. 2.5 to 2.7 mm. (3). 



2. Internal barrier consisting of a columellar, 3 or 4 basal 



folds and one above the periphery. Japan. 



8. nipponica. No. 14. 



Barrier consisting of a columellar and two basal folds. 



Quelpart Island. S. hirasei, No. 13. 



3. Umbilicus small, contained about 9 times in the diameter ; ' 



