36 Art. 6.— M. Yökoyama: 



Fossil occurrence. — Miyata Zone (Motowada); Yokosuka' 

 Zone (Otsu and Yokosuka); Koshiba Zone (Koshiba); Upper 

 Musashino of Musashi. 



Living. — Northern Japan (Yamada Bay) and Sakhalin. 



93. Leptothyra purpurescens, (Dunkeu). 

 Pl. V. Fig. 22. 



Leptothyra purpurescens. Tkton, Man. Coocb., X, p. 251, pl. 69, %. 24. Pilbbrt, Cat. 

 Mar. Moll. Jap., 90. 



Collonia purpurescens. Dunker, Index Moll. Mar. Jap., p. 129, pl. XII, tigs. 1-3. 



This is a globose shell with five rounded whorls separated 

 by subcanaliculated sutures and spirally sculptured by unequal i 

 graniferous riblets at unequal distances. Between the riblets there 

 are one or several fine close spiral stria 1 . The aperture is round 

 and pearly within when living. The purple colour is more or less 

 preserved in our specimens which are in general larger than those 

 of the preceding species, height and diameter being about 11 

 millim. in the largest one. Rather frequent. 



Fossil occurrence. — Miyata Zone (Mukaibatake, Harashita 

 and Maruyama-no-saka in Shimo-Miyata, Kami-Miyata and Moto- 

 wada). Upper Musashino of Kazusa and Shimosa. 



Living. — Japan (Dunkeb). 



94. Leptothyra cf. paucicostata, Dall. 

 Pl. A'. Fig. 15. 



A single imperfect specimen much water-worn and with' 

 fractured outer lip. It is a small shell, 8 millim. in height and 

 diameter, depressed-globose, solid and imperforate. The whorls 

 are few, rapidly growing, the last one having two strong, elevated 

 spiral ribs above the angulated periphery separated by concave 

 interspaces. Of these two ribs, the lower one is somewhat larger, 

 while the one forming the periphery is about the same size as the 

 upper rib. The base is flattened near the periphery and orna- 

 mented with five spiral threads. The place where the umbilicus 

 ought to be, if it is present, is somewhat sunken. Lines of growth 

 very distinct. 



