Fossils from the Upper Musasliino of Kazu&a and Shimoea. \Q5 



^1i7. Zjitnopsis àiipponica, Yokoyama. 

 PL XVII, Figs. 16, 17. 



Shell very small, moderately thick, longitudinally oblong, 

 somewhat oblique, convex. Anterior and posterior margins only 

 a little cm'ved and subparallel; ventral rounded. Surface radiately 

 striated; striae many, nearly straight, subequal, with equal or 

 broader interspaces and cut by incremental lines, the points of 

 intersection being more or less grain-like. Hinge-line about as long 

 as shell-length, with about three teeth in front of ligamental pit 

 and about five behind. Beaks small, pushed a little forward. Inner 

 surface with fine radiating lines within the palliai line. Inner 

 margin flattened and smooth. Length 2.9 millim. Height o.5 

 millim. Depth of each valve 1.3 millim. 



Fossil occurrence. — Kioroshi (very rare), Shito (do). 



Family Ledidae. 



Genus L,EDA, Schumacher. 



338. Leda eon fusa, Hanly. 



PI. XVII. Fig-. 4. 



Leda confusa. Hauley in Sowerby's Thes. Conch., Ill, Nucnlidœ, p. 119, pi. 228. fig. 

 85. Lischke, Jap. Meeresconcb., Ill, p. 109. Dunker, Inck Molk, p. 238. 

 Brauns, Geol. Env. Tokio, p. 45. Pilsbry, Cat., p. 56. 



Hanley describes this shell as follows: 



Beaked-oval, convex or subventricose with a shining ash- 

 coloured epidermis, closely, regularly, and concentrically grooved 

 throughout (the dorsal areas excepted); sulci shelving in front, 

 their intervals converted into flattened costa^ on the umboes and 

 towards the umbonal ridge which latter is neither elevated nor 

 defined in front. Sides equal, or very nearly so: Anterior extremity 

 rounded; posterior side rather abruptly beaked, the tip, which is 

 either in the middle or just above it, upturned and sharply angular. 

 Front dorsal slope very slight, convex with a sudden terminal 

 retusion. Hinder dorsal slope moderate, at first straightish or 

 plano-convex, eventually rather suddenly incurved. Ventral margin 



