98 Art. 6.— M. Yokoyama: 



to say, this same species is figured in Tryon's Manual (vol, XII, 

 pi. 63, figs. 40, 41) much higher, with a larger summit and a 

 more oval aperture, so that it looks like a different species. 

 Therefore, in absence of real specimens for comparison, it is 

 impossible to determine whether our fossil is identical with it or 

 not. On this account I deemed it more advisable to describe the 

 former as a new species. But the close relationship existing 

 between the two is undeniable. 



Fossil occurrence. — Koshiba Zone (Koshiba). 



Genus FJmarffinttla, Lamarck. 



113. Emarginula fragilis, Yokoyama. 



Pl. VI. Fig. 10. 



Shell thin, depressed-conic, ovately oblong in outline; apex 

 subposterior, prominent, recurved with front slope convex and 

 posterior slope nearly straight and steep. The sculpture consists 

 of radiating riblets and concentric stria?. Radiating riblets 

 numerous, about thirty in number with an interstitial riblet 

 between, which generally does not attain the apex; between the 

 riblet and the interstitial one there are still one to three equal or 

 unequal fine striae. Concentric stria? very fine, tolerably close 

 together, especially distinct in the interspaces but going over the 

 riblets, making them more or less granulate and rough. Posterior 

 slit deep. Cicatrix elevated, bounded by two sharp ridges and 

 divided into rectangular pits by transverse septa. Apertural 

 margin crenulate. Height 8, 5 millim. , longer diameter 14 millim. , 

 shorter diameter 10 millim. 



A single specimen. 



This species comes closest to Emarginula cancellata Phil. 

 (Thes. Conch., Ill, pl. 246, figs. 15, 16) of the Atlantic, but is 

 more elevated and the posterior slope steeper. 



Fossil occurrence. — Miyata Zone (Harashita in Shimo- 

 Miyata). 



