Fossils from the M iura Peninsula and its Immediate North. 113 



The shell is transversely oval, very thin, compressed, with 

 the anterior side longer than the posterior. The anterior margin 

 is rounded, while the posterior is arcuate and at its junction with 

 the ventral margin bluntly angulate. The hinge consists of two 

 small diverging teeth, of which the anterior in the left valve and 

 the posterior in the right valve is bifid. The so-called Tellina-fold 

 is not so marked in this species. The surface in grown specimens 

 is concentrically striated. The umbonal edge running from the 

 beak to the postero-ventral angle is very obtuse. The palliai 

 sinus is large and deep, almost reaching to the anterior adductor 

 impression. 



One left valve and one small right valve. The former 

 measures 2o millim. in length and 14 millim. in height. 



Fossil occurrence. — Miyata Zone (Nagai) and NaganumaZone 

 (Naganuma); Upper Musashino of Musashi, Kazusa and Shimosa. 



Living. — Central and Western Japan. 



138. Tellina ojiensis, Tokunaga. 

 Pl. VII. Figs. 16, 17. 



Tellina ojiensis. Tokunaga, Foss. Env. Tokyo, p. 44, pl. II, figs, 34 a, a', b. 



The shell is rather small, not very thin, compressed, ob- 

 liquely subovate, somewhat inequivalve and inequilateral, the 

 posterior side being a little shorter than the anterior. Anterior 

 and posterior dorsal margins sloping, the posterior more steeply 

 than the anterior. Anterior margin rounded and passing gradu- 

 ally into the broadly arcuate ventral margin. Postero-ventral 

 angle obliquely truncate. The surface is covered with line, 

 regular, concentric grooves which, at the obtuse umbonal edge, 

 abruptly curve upward. Posterior fold rather weak. Of the two 

 cardinal teeth, the anterior in the left valve and the posterior in 

 the right valve is bifid. Lateral teeth two, one on each side. 

 Palliai sinus very large and deep, reaching nearly to the anterior 

 adductor impresion. Rather frequent. The largest left valve in 

 our possession measures 19 millim. in length of which 8,5 millim. 



