Ö Art. 5. — Mata jiro Yokoyama : 



of British Columbia near 51° N. Lat. and at a depth of 240 fathoms 

 where the temperature of the water is 7°C. Puncturella conica is 

 now living only near the Falkland Islands. Leda ramsayi is found 

 in New South Wales, but at a depth of 950 fathoms. Also all the 

 others are now living north of Tokyo Bay, and the three species 

 of Lima before mentioned, though existing near Central Japan, 

 have never yet been met with in the shallow waters of the 

 coast. Although the boreal forms together with these deep-water 

 ones make up about one-half of the living species, there is not a 

 single one which is limited to the warmer seas. Moreover, the 

 occurrence of such genera as Tricliotropis and Astarte among the new 

 species clearly indicates that the tempei'ature of the waters in which 

 the Koshiba shells had lived must have been a pretty low one. 



Now what makes this boreal character of the Koshiba fauna 

 the more important is the less boreal nature of the MollusccC-^ of 

 the upper Pliocene found in the immediate neighbourhood of 

 Tokyo, at Oji, Shinagawa, Tabata, etc., which, when compared 

 with the recent, are still boreal enough. From these facts, I am 

 forced to conclude that the climate of Central Japan during the 

 Pliocene Epoch was on the whole colder than now, and indeed, 

 colder in the earlier than in the later part of it. This is quite in accord- 

 ance with the conclusion already arrived at by Prof. Nathorst"-^ 

 from studying our Pliocene plants. This eminent palœobotanist 

 recognized plants of the said epoch occurring in a rock exposed at 

 the sea-coast near Yokohama and also at Mogi*-* as corresponding 

 to those now growing on our higher mountains and not on the 

 lowlands, as the situation of the fossils would naturally suggest; 

 and although he does not touch the question of the rise of tem- 

 perature in the course of the Pliocene, he advances the view that 

 the Yokohama plants are probably upper Pliocene and are younger 



1) These fossils have been studied by Dr. Tokunaga and the results given in bis " Fossils 

 from the Environs of Tokyo," article 2, vol. XXI of this journal. TJd fortunately he took them 

 for Diluvial, probably led by the boreal nature of the fossils of the same age in Europe, which 

 can not be, for they contain at least about 10% of extinct form=. Tokunaga himself describe» 

 more than 20% of extinct species. 



2) Contribution à la flore fossile du Japon, 18S3. Zur fossilen Flora Japans. 1888. 



3) Xear Nagasaki. 



