Fossild Erom the M iura Peninsula and its Inimendiate N'.tiIi. [■]>] 



15 millim. in depth. It is markedly more quadrate than the 

 shells figured by Lischke. As to the external sculpture, I have 

 to add that in the anterior half of the shell and near the ventral 

 margin there is a small intermediate rib which continues only fora 

 short distance in the direction of the beak. The palliai sinus is 

 short, triangular and blunt at end, as descrihed by Lischke. 



Another example which is a right valve 35 millim. in length 

 and 29 millim. in height is also subtruncate at the hinder end, and 

 the anterodorsal margin is more steeply sloping than in most 

 specimens, so that the shape approaches a trapezoid. 



Fossil occurrence. — Miyata Zone (Kami-Miyata and Nagai); 

 Yokosuka Zone (Yokosuka and Otsu). Upper Musashino of 

 shim osa. 



Living. — ('entrai and Western Japan. 



Genus Chione* Megekle von Mühlfeldt. 



149. Chione isabellina, (Philippi). 



Pl. VIII. Fig. 13, 



Chione isabellina. Deshayes, Conch. Brit. Mus., I, pl. 124, no. 17. Du nker, Index Moll. 

 Mar. Jap., p. 198. 



Venus isabellina. Philippi in Zeitsch. f. Malakoz., p. 188, no. 65, Abbild. Ill, p. 83, no. 5. 

 Venus, pl. x, fig. 5. Pfeiffer, in Syst. Conch. Cab. Mart. u. Chenin., XI. pt. 1, p. 194, pl. 25, 

 fig, 9. 



Shell roundly trigonal, thick, inequilateral, the posterior side 

 about twice as long as the anterior. Anterior end generally round- 

 ed, posterior end subangulate or subtruncate; postero-dorsal 

 margin somewhat convex and sloping, antero-dorsal margin slightly 

 excavated. The sculpture consists of concentric erect laminae 

 which are distant, ten to thirteen in number besides several near 

 the beak which are simply rib-like, and separated by wide flat in- 

 terspaces with only concentric lines of growth. These laminae in 

 the left valve stop suddenly on reaching the areal edge, while in 

 the right valve they continue a little into the area. Lunula 

 ovate, laminated, the laminae looking like continuations of the 

 dorsal ones, only interrupted by the boundary incision. Area 

 lanceolate, most developed in the left valve, longitudinally striated. 



