Dosinia exoleta L. will be proved in the following pages, and Cardium rauticum 

 Eeeve, all of which have been found frequently and in more than one locality, 

 and serve to illustrate sufficiently, what has been said about tlie character of these 

 strata. 



The quaternary formation looses the character which it exhibits in the 

 plain, whenever we ascend a few hundred feet above the level which it has near 

 the sea side, in the environs of the bay of Tokio. The valleys of the rivers are 

 terraced also there, but the differences between the true diluvial and the true 

 alluvial formation disappear, and instead of them, a formation is developed 

 containing large pebbles, shingle and sand mixed with loose, impure soil, such as 

 we frequently find along the slopes of steep hills or moimtains. As this formation 

 passes insensibly into very recent deposits, there can scarcely be any doubt 

 about its being partly of recent origin, and corresponding to the undoubtedly 

 alluvial deposits of the lower part of the river valleys. But this cannot be said 

 of the totality of these loose quaternary conglomerates, as there is evidence of 

 organic remains in them which belong to extinct mammals. Though the species 

 could not be always ascertained there can be no doubt about the genus Elephas 

 (v. Chapter 3.) occurring not unfrequently in the beds described above, which, 

 as scarcely needs be mentioned, cover unconfonnably all the other formations, 

 palaeozoic or tertiary, with a coat which sometimes has many metres of thickness, 

 whilst, in other instances, it is partly or entirely eroded and taken off by the 

 waters, or even may have been prevented by them from being deposited at all. 

 As good examples of such deposits we may mention again the districts of Chichibu 

 and Komagori, the latter exhibiting moreover the passage between the above- 

 mentioned conglomerates and the more clayish soils fonning the upper part of 

 the deposits of the plain, a passage gradually appearing just beyond Hanno. 

 Having thus encircled the large plain of Tokio and characterized the mountains 

 in its circmuference, upon which, therefore, its deposits are somewhat dependent, 

 we may proceed to describe the plain itself and the parts into which it is to be 

 divided. 



Of course the difference is most obvious between the river-valleys themselves 

 and the parts of the plain in which the valleys are cut. The smaller valleys 

 and side-valleys, and on the other hand all the innumeniblo smaller or larger 

 portions of the higher plain left lietween the rivers and rivulets, exhibit a 

 similar if not identical character. This uniformity in character of both of these 

 formations relieves us from enumerating all those rivers, which in a very great 

 number descend from the water-ridges towards the plain and reacli the sea, 

 partly in the Ixiy of Tokio, i^rtly in the adjacent jxirts of the oce^in. The 

 largest of all those rivers, the Tonegawa, is renowned for the partitions which 

 take place about 40 miles from the mouth. Some of its arms run into 

 the open sea, the largest of tlium fonning a sort of lagoon-district liarro<l from 

 ocean by sand-banks, similar also in sonic respect to the Nehrung wjiich severs 

 the mouths of the Baltic rivers called Haffs, from tlie open sen. H^-sides I lie 



