Fossils from the Upper Musashino of Kazusa and Shimosa. 49^ 



Family Marginellidae. 



Genas IllAKC>IN£L.IiA, Lamarck. 

 48, Marffinella cotanuigo, Yokoyama. 



PI. n. Fig. 6. 



Shell minute, rather solid, ovoid, the greatest diameter being 

 a little above the middle of the shell, smooth. Spire concealed. 

 Apex rather rounded. Aperture as long as the shell, narrow. 

 Inner lip with four plaits of which the lowest is the strongest and 

 most oblique ; the next upper one is also prominent but more 

 horizontal, while the two uppermost which are nearly horizon- 

 tal are thin and often indistinct. Outer lip thickened, receding 

 both above and below, smooth within. Rare. The largest example 

 measures 2 millim. in height and 1.5 millim. in diameter. 



This shell looks like Jlarginella mimita Pfr. (Tryon, 

 Man. Conch., V, pi. . XII, figs. 60-63) of the Atlantic which, 

 however, has the outer lip denticulate within. 



Fossil occurrence. — Shito. 



Living. — Central Japan. 



49. JflarghieUa perorulutn, Yokoyama. 

 PI. 11. Fig. 7. 



Shell small, ovoid, rather thin. Spire hidden. Apex very 

 obtusely pointed. Body-whorl smooth, broadest a little above the 

 middle. Aperture as long as the shell, somewhat dilated in front. 

 Inner lip with four plaits of which the lowest is the strongest, 

 while the other three are nearly equal in size and all quite distinct. 

 Outer lip not thickened, sharp, smooth within. Height 2 millim. 

 Diameter 1.2 milhm. 



This shell closely resembles Marginella ovulum Sow. (Thes. 

 Conch., I, pi. 78, fig. 188) from Austi-alia which, however, tapers 

 more sharply downward. 



Fossil occurrence. — At Shito, but rather rare. 



