Fossil.« from tin' Mjura l't-in nsiila ;ihd its Immediate North. \'.Vi\ 



Shell small, moderato in thickness, almost orbicular, nearly 

 equilateral, rather convex, concentrically and radiately striated; 

 concentrical striae often elevated and lamellar: radiating striae 

 fine, numerous, often obliterated, especially in the middle portion 

 of the shell, divergent at the anterior as well as at the posterior 

 side. Inner margin finely crenulate. Lunula ovate, dee]). The 

 proportion of length to height is more or less variable, some shell 

 being higher than long. But normally the length is a little 

 greater than the height. Our largest example is a left valve 

 10 millim. both in length and height, and 4 millim. in depth. 

 Not rare. 



Fossil occurrence: — Miyata Zone (Okine); Yokosuka Zone 

 (Yokosuka); Naganuma Zone (Naganuma). Upper Musashino of 

 Shimosa. 



laving: — Northern, Central and Western Japan; Ryukyus; 

 Bonins; New South Wales. 



1<j7. Lucina borealis, (Linné l. 

 Pl. X. Fig. 7. 



Lucina bureali*. Forbes and Hanley, Brit. Moll., II, p. 46, pl. 35, fig. 5. Pfeiffer in 

 Syst. Conch. Cab. Mart. Chemn., vol. XI, pt. 1, p. 256. pl. 9, fig. 1. Wood, Crag Moll., Biv. p. 

 139, pl. XII, fig. 1. Ntst, Conch. Terr. Tert. de Belgique, p. 176, pl. XIX, fig. 2, Brauns, 

 Geol. Env. Tokio, p. 44. Tokunaga, Foss. Env. Tokyo, p. 52. 



Lucina radula. Philippi, Enmn. Moll. Sic, I, p. 35, pl. Ill, fig. 17, II, p. 25. Gould, 

 Invert. Massach., p. 69. 



Lucina anliquata. Nyst, Coq. Foss. de Belg., p. 128. pl. 6, tig. 7. 



Lucina flandrica. Nyst, Coq. Foss. de Belg., p. 127, pl. 6, fig. 6. 



Venus borealis. Linné, Syst. Nat., ed. 12, p. 1134, No. 143. 



This is a very common shell in the Upper Musashino of 

 Oji; hut it is here represented by only a few specimens. The 

 one from Yokosuka with both valves complete is 30 millim. in 

 length and height, and 16 millim. in depth, nearly orbicular in 

 outline and with the usuall lamellar concentric striae whose 

 interspaces are ornamented with fine concentric lines. No 

 essential difference is to he found between it and the < >.ji specimen 

 or the European ones. 



Fossil occurrence in Japan: — Miyata Zone (Shiöj.Q- Miyata); 



