78 



very lately, aiid to 1x3 extinct. IVt'jvsca drudgin;^ may inde«.-«!, ns hn» been 

 the case with this spcfies, reduce llie numlier of rciilly e.vtinrt tertiary form«; 

 liiit tliis is a fact which is applii^^iMe to all tlie younger tertiary de|x>sil8. It 

 proves indeed tliat an extinct fauna mnst be considered a<» such even if it dot>B 

 not contain any other but living «[wciif«, whenever a larger part of these ii|)ecie8 

 does not bi-long to the re.'ont f.iua\ of (he »ime zoogi'D'^niphiail jirovince or region. 



Of course we find also iti the cla.ss of Conchifera many sjiecies which aro 

 Atlantic sus well ivs Pacific. Two of the bivalves, Saxicava nrctica L. and Mya 

 arenaria L., are circumpolar: one, Lasaea rubra Mont., is cosmopolitan. A grcnt 

 many are also fossil, especially of those common to lioth the western and eastern 

 ocean, and I think it will not appear a very jwinwloxial n'sult that — aided 

 Iiy a rich supply of s|)ecimens— I added to their numU'r Diminia cxolcta L. 

 and Nucnla Coblioldia) Bow. and r'plared to it TajK-s decussatus L., known from 

 the .Japanese coast ivs Dosini.i ji|ionica and Troscheli, as Nucnla mirabilis and 

 insignis, ami ns Tajies riiilippinarum. In this resix-ct, I am indeed fidly con- 

 vinced that in Japan exactly the reverse will take place of what Tjisclike say« to 

 Ik; commonly the case, viz. that in every fauna which is iin|terfectly known a 

 further revision will probably rcibicc the numlwr of the /orei';/»» form», or of 

 those sjiecies which arc said to bo itlentical with fonns of another |iart of the 

 globe. Lischke himself has shown by too many exam])!!-« that the miirino mol- 

 luscous fauna of Ja|)an is— just as the fauna of other classes of animals— paln)- 

 arctic. Perhaps it would appear still more so if wt; knew the real distribution 

 and geographical range of some genera and sj)ecie8 now mostly coiifine<l to 

 southern latitudes, as for instanci; Myatloni. At all events, wo have in the 

 fauna of Oji, Tokio, Kanagawn, Yokohama, Takigashini elements which do not 

 agR'c with the actual Japanese fauna, and the nuuil>er and importance of these 

 elements is so great as to remove all i>os8ibility of their ever lK?ing efface«! by 

 discoverii's of recent Japanese shells. I need scarcely add that some of the specie« 

 which are extinct on the Kast-Asiatic coast, occur very frequently it) the tertiary 

 layers, e. g. TiUcina liorealis, Diplodonta trigonula, Tiimo|)Bis aurita. 



In these a« well as in many other res|)ect8 the JaiMinese shell-layers 

 discussed above have the galtest resendilance to the Crntj, and next to it 

 with till' younger Subappenine de|)osil8, whilst the nx-ks resemble very closely 

 the Euro|K*an Faluns, a fonnntion, by the way, not at all limited to the western 

 CO ist of Fmnce. Glacial dejHJsits have no more affinity with the Oji deposit« 

 than with the English Crag it.sclf, and it would 1x3 very easy to mat<'h the 

 'arctic' s|K'cies undoubtedly contained in these deposits by others — ('yclina sinen- 

 sis, Ai-ca granosa, Monoptygma, Myadora, or even Diphxlonta trigoniihi— which 

 jxiiiit mon^ to the south. And thus we slunild at last be obligi«d to recur to the 

 cxplanatinns given alK)ve ou this subject. — 



If, however, all these vwisoiis shouM jiot seem tt) give sufficient evidence of 

 tlu-se views, the localities described in the seventh chapter will do so in a 

 perfectly satisfactory manner. 



