27 



in the introductory chapter, have an angle of dipping mostly of 30°, or rather 

 from 30 to 40 ', directed towards \V 30° E ; in a few instiinces, near the hordei-s 

 of the hasin filled by those strata, il amounts to 55' or even a little above, the 

 direction changing to due North. As it has been already stated and will be 

 discussed below, the fossils contained in these beds are to so great an extent tlie 

 same as those of the strata which in the Tokio-i)lai!i appear directly below the 

 above-delined line of uncouformability, that there can be no doubt about all 

 these layers belonging to one and the same formation. 



This, of course, could not be affirmed without some deeper study of the fossils, 

 and I think, it is i^uite necessary for the advancement of our knowledge of tiiis 

 highly important formation to give the results of the observations thus tar made 

 upon it, without attemi)ting for the present to make them quite complete. 

 Indeed, it does not seem advisable, to extend at once those researches to other 

 animals than mollusci, or to the fossil plants occasionally found in these 

 uj^permoöt tirtiary deposits of the environs of Tokio, as we may call them quite 

 safely. Although we iind almost always fragments of stems of monocotyledons, 

 dicotyledous and gymnospcrmous i)lants, and although a few nice small speci- 

 mens of corals, some sea-urchins, as c. g. Echinocyamus and Scutella found at 

 OJi, and even occasionally, for instance in the province of Miao (Togiiri and 

 Tsukiyoshi) some crabs or fish may be found between the remains of mollusca, 

 yet the number of the latter so far exceeds that of other organisms, that we may 

 now confine our attention advantageously to an analysis of the mollusca. 



In giving the list of the fossil shells, I think it advisable ilrst to separate them 

 according to the localities. I hope thus not only to leave no doubt whatever 

 about the unitbrmity of all those localities and shell layere, but also to give a 

 full account of all the facts peculiar to each of them. 



The locality firet to be mentioned is Oji, see fig. 4, a village in the neigh- 

 bourhood of Tokio, situated beyond that part of the town which is called Hongo, 

 and nearly N.X.W. from the centre of the town. The distance of Oji from 

 ■Nihonbashi is about 2 Pii., from the centre of Hongo about 1 Hi (one Hi being 

 nearly equal to 4 kilometres j. 



Arriving at Oji, we see first a cutting containing sandy conglomerates of the 

 lower diluvial formation under a cover of the upper diluvial loam, next to the 

 road descending from the height of the plateau down to the rivulet passing 

 through the vilhige. After crossing the river and ascending the plateau on the 

 other side, we have the same formation, viz., upper and lower diluvial strata. 

 We see here, however, some clayish layers between tlie conglomerates and simds. 

 Passing on a little more to the west, we find the deep cutting in which a corn-mil! 

 is bituated, and in this"cutting, very near its bottom, are those shell layei-s, which 

 are richer iu shells, individuals as well as species, than any of the other localities 

 to Ije mentioned. It is obvious from the very first glance at the place or at its 

 figure (PI. I, fig. 4) that we cannot possibly have to deal here with any accumu- 

 lation of shells mode by men ; the thickness of the diluvial deposits, hero still 



