Fossils from the Upper Musashino of Kazusa and Sliiraosa. 169 



Order Anomalodesmacea. 

 Family Cuspidarudae. 



Genus CUSPIDAHIA, Xarclo. 

 273. Cuspidaria ligtila, Yokoyama. 



PI. XIV. Figs. 3, 4. 



Shell small, thin, moderately convex, transversely piriform, 

 somewhat inequilateral with anterior side a little shorter than 

 posterior, rounded in front, rostrate and truncate behind. Antero- 

 dorsal margin slightly concave, ventral broadly convex except 

 near posterior end where it is somewhat convex. Surface convex 

 in general, being rather compressed only in the rostrum. Beaks 

 very small, .directed backward. A long lamellar tooth is present 

 both in front of, and behind, the l)eaks. parallel with the 

 hinge-margin. Sculpture pressent only on the area formed by a 

 keel running from each beak to postero- ventral corner, consisting 

 of fine concentric striae crossed and cut by fine impressed lines. 

 The following are the measurements: 



Length. Height. Depth. 



Eight valve 6.4 millim. 3.6 millim. 1.5 millim. 



. Left „ 6.1 „ 4.0 „ 1.4 „ 



Fossil occurrence. — Shito (rare). 



Family Lyonsüdse. 



Genus tYONSIA, Turton. 



374. Lyonsia praefenuis, Dunker. 



P], XrV. Figs. 9, 10. 



Lyonsiu pnztenuis. Dunker, lud. Moll., p. 180, pi. VII, fig. 12. Pilsbry, Cat., p. 137. 



The shell in very thin and fragile, transversely ovate, rather 



gibbous, rounded in front, produced and obliquely truncate behind, 



and ornamented with radiating costulae on the surface. 



Only three isolated valves, more or less fractured. The least 

 imperfect is a right valve, 14.7 milhm. long, 9.3 millim. high 

 and 3 millim. deep. 



