抄録
The author reviewed his former studies on the minute structures of fossils in Japan. Minute structures of carapace in some recent and fossil crabs are investigated in this paper, based upon the photographs of electron-microscope. Carcinoplax longimanus-the recent species shows the horizontal and inclined structures in the section of carapace, in which a canal system may be found. The diameter of the canals is ranging from 1 to 3 microns. Cancer minutoserratus from the Tatsunokuchi formation in Sendai shows the assemblages of polygons with linear structure, in the surface of carapace. Carcinoplax prisca from the Miocene formation of Miyazaki Prefecture shows sub-rounded polygonal assemblages on the surface of the carapace. Notopocorystes stokesii from the Cretaceous Greensand of Cambridge shows rounded polygonal assemblages on the surface of carapace. It seems that fossil crabs have the tendency of orthogenetic evolution from the rounded polygonal assemblages in the minute structure of the surface of carapace to the angular ones, but the mutual relation of the minute structure of carapace in the recent species between the surface and the section is not yet clear. In future, it is most necessary to observe the sections of carapace of fossil crabs by electron microscope, and subsequently to study the relation between micro-structures of inorganic materials of carapace and organic materials in fossil crabs.
