PREFACE. 



The geology of the environs of. Tokio is a subject which has undoubtedly a 

 very high interest for visitors and residents of Tokio or Yokohama, but above 

 all for the Japanese students of geology to wliom it offers some difficulties 

 which no one. as far as I know, has tried to obviate. Unfortunately, I have not 

 at hand Professor Heins last publication about Japan, the only one I have 

 before me being his paper on the Fuji-no-yama contained in the 25th volume of 

 Petermann's ' geogi-aphische Mittheilungen'; but as the problems which form 

 the main subject of this memoir ai-e chiefly of a paleontological character, the 

 author of the Japanese geography can scarcely have alluded to those difficulties. 

 Although Dr. E. Naumann's paper concerning the Tokio plain, contained in 

 the same volume of the 'geographische ^littheilungen,' makes also no allusion 

 to them, yet I have been obliged, in treating the same subjects, to advance 

 opinions, as it will be seen, partly agreeing with, partly diverging from those of 

 Dr. Naumann. A paper about the fossil elephants of Japan being under prepara- 

 tion by the same author, I preferred not to recur to the preliminar)' notices 

 given by Dr. Naumann on this subject in the periodical of the ' Ostasiati.sche 

 Geselltchaft. ' 



By far the greatest difficulty was the deteiTnintion of the fossil shells 

 mentioned in chapters 4 to 7, a difficulty increased by the want of several 

 of those books which ouy;ht to have been consulted. This circumstance is 

 also the reason why I could not give a fuller account of all the organic remains, 

 and confined myself to giving descrij)tions only of the Mollusca contained in the 

 pliocene beds of Tokio and Yokohama. Of these, however, a few species were 

 also excluded who.se condition would not admit of an exact determination. 

 From the molluscous fauna the conclusions concerning the horizon and nature 

 of the stmta were drawn. As a similar way has been followed by other authors 

 in a great many instances, I think I have committed no error in doing the same 

 in a case which was not only of great importance, but also did not promise to 

 yield other means of solving the problem. 



The books mostly consulted were Lischke's japanische Meeres-conchylien, 

 contained in three volumes, published by Fischer, Ca.ssel, in the yeare 1SG9 and 

 1874-1S7."). This work, richly illustrated and critically written, mentions (and 

 mostly de.«crilj€s) 429 sjHJcies of Japanese moUusca, and so ramie u]i lor the want 

 of otlier books, e. g. Duuker's and Schrenck's work.s on Japanese Jlolliisca. 

 The local fauna besides was partly given in Oould'x Otia conchologica, or, 

 descriptions rif shells and molhisca, from 1S39 to l.st')2, Boston 18()2, to which 

 the Plates of the Mollusca from Wilke's exploring expedition, by the saim- 



