Fossils from the Upper Musashino of Kazusa and Shiuiosa. 79 



middle, also with a cord at the angle; the i^urface between this 

 angle and the periphery is flat with spiral threads on it, while that 

 between the same and the umbilical margin is somewhat convex 

 and furnished with two spiral threads. All these tlneads together 

 with the angle-cords are crossed by incremental striae, the points 

 of intersection I)eing bead-like. Umbilicus large with margin 

 crenate. Aperture quadratic. Height 1.5 millim. Diameter of 

 shell 3.5 millim. Diameter of umbilicus 1.2 millim. 



A single specimen. 



Fossil occurrence. — Shito. 



Family Rissoidae. 



Genns KISSOA, Freminville. 



120. Rissou (dnf/ula) ptebeja, Yokoyama. 



PI. IV. Fig. 3. 



Shell small, lurrete. Whorls about nine, the first three 

 embryonal and very small, the succeeding more or less angulate at 

 about one-third distance from the lower suture, the surface both 

 above and below the augle being a little convex. Sometimes the 

 angle may be rather indistinct in wliicli case the whorls appear 

 strongly convex. The sculpture consists of very faint spiral striae 

 only visible with a magnifler under a good reflection of light. 

 Periphery rounded. Base abruptly narrowed, convex, smooth. 

 Aperture ovate. Inner lip covered with a thin glaze. Outer lip 

 thin, sharp. Height 5 millim. Diameter 2 millim. 



The specimens are frequent, but none of them has the outer 

 lip perfect, owing to its thin and fragile nature. 



Fossil occurrence. — Shito. 



Genus KISSOI^A, d'Orbiguy. 

 10Î5. liissoina {Jfloerchiella) niati,^ahiaitti, Yokoyama. 



PI. IV. Fig. 4. 



Shell small, ovately fusiform, rather solid. Whorls six, the 

 first two smooth and rounded, the succeeding somewhat convex. 



