抄録
The writers found recentry many nodulose tubes from the basal part of the upper Narita formation (late plistocene) at the east corner of Shimoyokoto village, Yokoto-Machi, Chiba-city, Chiba prefecture. The tubes consist of mud and sand mixture, some one is preserved in good condition and remains callianassid crustacea (Callianassa japonica ORTMAN) in it. These specimens had been kept of nearly in living position, that is, they have large and small chelipeds in pairs and fragile jointed waking appendages. On the other hand, the remains which were found outside of the tubes had been polished and detached by water current and some of them has small holes on the surface which probably been challenged by scavenger or certain carnivorous animals. This finding suggest, more or less, post-mortem changes. In short, the writers are strongly inclined to consider that the good preserved individuals in tubes might have been autochthonous fossils, and the others died outside of original burrows.
