Dr. H. Yabe — New Pleistocene Fauna from Tokyo. 213 



Tapes sp. Yoldia sp. 



Cardium braunsi, Tok. Area tenuis, Tok. 



C. calif omiense, Desh. Pectunculus albolineatus, Lischke. 



Phacoides aft', borealis, L. Pecten tokyoensis, Tok. 



Diplodonta pacifica, Tok. P. laqueatus, Sowb. 



Nuctda insignis, Gld. 



Of these eight species of Gasteropoda and twenty-six species of 

 Lamellibranchia (Pelecypoda), Natica clausa, Panopcea yenerosa, Tellina 

 venulosa, Saxidomus nuttalli, Venus stimpsoni, Area tenuis, and 

 Pectunculus albolineatus are predominant, whereas Solen krusensterni, 

 Mactra sulcataria, Tresus nuttalli, Tellina nipponica, Diplodonta pacifica, 

 and Pecten tokyoensis are very common. 



The comparison of these two lists of fossils shows that only four 

 species — Nassa japonica, Rinyicula arctata, Solen krusensterni, and 

 Tellina yedoensis — are common to both ; whilst the complete absence 

 of the typical estuarine forms is a distinguishing feature of the newly 

 found molluscan fauna. The number of the common species may 

 perhaps be somewhat increased by more extensive and cautious 

 collecting of fossils from both localities ; but the striking difference 

 of these two faunas seems to be quite apparent. 



On the other hand, the new fauna from Tabata has nearly all the 

 species in common with the fauna from the principal shell-bed of Oji 

 and Shinagawa, which decidedly represents a slightly lower horizon, 

 as mentioned above ; the only exception is Tellina venulosa, which is 

 so abundant in Tabata, but still unknown from other fossiliferous 

 localities in and near Tokyo. This difference is more remarkable 

 when we take the fact into consideration that this species, now living 

 in great abundance in the surrounding seas of Hokkaido, and rarely 

 found in a diminutive form along the more southern coasts washed by 

 the cold Lyman current, is found in multitudes in the shell-sand of 

 the Narita Series, which is extensively developed in the province of 

 Shimosa and in the part of Musashi lying east of Tokyo. The shell- 

 sand of the Narita Series is considered by Tokunaga to be younger 

 than the shell-beds of Tokyo, taking together the shell-beds of 

 Shinagawa, Oji, and Tabata, while others think them of nearly the 

 same age. 



It is necessary here to introduce a short account of the ISarita Series 

 from one of my former articles in Japanese, supplemented by later 

 observations. 



In the extensive tract of loam, lying east of Tokyo, is a subaerial 

 deposit, without any trace of stratification and sometimes with thin 

 irregular layers of nearly decomposed pumice, is underlaid by a thick 

 complex of marine sand with a little intercalation of clay and 

 argillaceous sand which for convenience sake I called " Narita Series", 

 from the reason of its typical development in the neighbourhood 

 of Narita in the province of Shimosa. The marine sand is sometimes 

 very fine-grained and sometimes coarse, even mixed with shingle, 

 composed chiefly of quartz fragments, and in great contrast to the 

 shell-bearing sand of Tokyo ; it is not tufaceous. Cross-bedding is 

 universal. The distribution of fossil shells in the sand is not uniform, 

 but they are found here and there in considerable numbers. 



