4 Art. 6. — M. Yokoyama : 



part. The lower part is typically developed in the peninsula of 

 Miura. Here again the Mollusca form the most important fossil, 

 though in one place, Yokosuka a lower jaw of Elephas namadicus l) 

 has also heen discovered. 



The position of the line of demarcation between the two parts 

 is at present uncertain, for, geologically, the whole marine series 

 is a single complex of layers conformably superposed one upon 

 another, and palaeontologically, the fossils found in the inter- 

 mediate place have not yet been fully examined. But, if that 

 line should ever be drawn, I think it will be somewhere near 

 Yokohama, perhaps a little south of it. Be the position as it 

 may, it is quite evident that the layers exposed in the Miura 

 Peninsula occupy a lower position than those of the plain, for the 

 latter which are nearly horizontal in the neighbourhood of Tokyo 

 gradually dip to north as we proceed southward, and already at 

 Sugita, Naganuma, etc., the angle is about 5°. And southward 

 from these places the angle grows slowly but constantly, so that 

 near Yokosuka it is already 20° to 30°, while in the southern half 

 of the Miura Peninsula, the layers after making several folds finally 

 dip south with very steep angles.' 2 -* 



Concerning the geological age of the upper part of the marine 

 series, opinions are divided. Brauns, as before mentioned, 

 pronounced it to be Pliocene, while Tokunaga, Yabe 3) and others 

 consider it to be Pleistocene. As to myself, I am not aide at 

 present to forward any opinion on it, as I have not yet thoroughly 

 studied its fossil contents. 4) Under such circumstances, I deem it 

 most expedient not to call the formation by age, that is to say, 



1) E. Naumann. Über die fossilen Elephanten der Vorzeit. Palaeotographica Bd. 

 XX Vin, Heft 1, 1881, p. 28. 



2) About the geology of the peninsula, see S. Yoshiwaka's Tokyo Inan Miura Han to 

 Chishitsu Kon (Geology of South of Tokyo and of the Miura Peninsula), Jour. Geol. Soc. 

 Tokyo, 1902, Vol. IX. 



3) H. Yabe. A New Pleistocene Fauna from Tokyo. Geol. Mag., Dec. V, Vol. VIII, 

 London, 1911. 



4) The treatment of these fossils will appear in a future paper. 



