Fossils from the Minra Peninsula and its Immediate North. 165 



according to the size of the shell. In a specimen about 20 millim. 

 Long we count five, but there is one only 35 millim. long and with 

 more than ten grooves. The posterior portion of the area is free 

 from grooves, ornamented only with straight lines parallel to the 

 hinge-line. There is a considerable variation in the form of the 

 shell. Rather frequent. 



The largest specimen in our possession is a left valve 47 

 millim. long, 27 millim. high and 13 millim. deep. 



Fossil occurrence. — Miyata Zone (Motoyashiki in Shimo- 

 Miyata); Yokosuka Zone (Yokosuka and Otsu); Kanazawa Zone 

 (Nojima); Koshiba Zone (Koshiba). Upper Musashino of Mqsasbi, 

 Shimosa and Kazusa. 



Living. — Northern and Central Japan. 



213. Area decussata, (Sowerby). 

 Pl. XVII. Fig. 5. 



Area decussata. Reeve, Conch. Icon., Area, sp. 81, pl. XII, fig. 81. Lischke, Jap. Meeres- 

 conch., I, p. 149. Syst. Conch. Cah., vol. VIEL, p. 144, pl. 37, figs. 2-5. 

 Byssoarca decussata. Sowerby, Proc. Zool. Soc. London, 1833, p. 22. 

 Earbatia decussata, Dünker, Index Moll., p. 232. 



A young right valve, 14 millim. long, 9 millim. high and 3,5 

 millim. deep. 



It is transversely oval, very inequilateral, dorsally somewhat 

 excavated in the middle, with numerous unequal, radiating riblets 

 crossed by concentric lines, some of which are rather coarse. 

 There is no sharp diagonal keel on the surface. The area is rather 

 narrow, with grooves parallel to the hinge-line. The shell is 

 rather worn and thin, but it seems to have been originally firm. 

 It agrees very well with the living specimens of the species named. 



Fossil occurrence. — Koshiba Zone (Koshiba). 



Living. — Western Japan; Philippines; South Sea; Indian 

 Ocean; Gulf of Guinea. 



214 Area stearnsii, Pilsbry. 

 Pl. XVI. Fig. 9. 



Area steamni. Pilsbry, Cat. Mar. Moll. Japan, p. 143, pl. LH, figs. 8-10. 



