04 ART. 2. S. TOKUNAGA. 



In the brownish clay of Oji and Shinagawa, plant leaves rarely 

 occur, while at Tabata the brownish as well as the bluish clay 

 contains great quantities of them. Below the clays is found a 

 bluish sand, which yields some moUuscan casts^' at Shinagawa 

 and Oji and numerous shells at Tabata. At the last locality no 

 bed lower than this sand is exposed. But at Shinagawa and 

 Oji, there is a sand with numerous shells, showing a wavy line 

 of boundary against the overlying sand on natural profiles. 



Brauns regarded this wavy line as an important demarca- 

 tion between his " non-fossiliferous zone" (in reality containing 

 shell casts at ()ji and Shinagawa) and the underlying shell bed. 

 However, as is well known, the surface of shell heaps constantly 

 disturbed by sea waves is usually not perfectly flat and horizontal, 

 but shows numerons depressions and elevations. The same thing 

 is also observable in strata, for instance in those of the Tertiary 

 of Sendai, Province of Bikuzen, where there are three shell 

 zones in a thick tufaceous sandstone, each shows a wavy surface. 

 On the eastern side of a railway cutting at Shinagawa, the line 

 is not always distinct, and the overlying sand, which does not 

 differ from the shell bed either in colour or hardness, sometimes 

 contains shells irregularly pushed in from the lower bed. From 

 the above facts it will be seen that the so-called line of demar- 

 cation is not of any great significance in the determinationf of 

 the age of the shell-bed. 



The bluish cla}' overlying the sand is to be considered as 

 belonging to the same geological epoch as the lattei-, for in 

 some places the clay alters its nature according to the sand, 



■^' Casts found at Oji and Shinagawa belong to J /'ca inflate Rvt:., I'ec'ten laqueatios Sow., 

 Pecluiu-Mlus nibo-linealus IjKE., Pcuiopœa rjeiwrosn (\lv., SaxidomuH imitai I. Coxkad, Tapex 

 rigidus (ild. and Mamwi na.-oitd Coxkad, etc. 



t Jl must be ]<v[>\ in mind liiat the layers now under discnssiuii lie ahnost horizontally. 



