Eridites undulatum壳体微细构造

利用偏光显微镜及扫描电子显微镜观察了假直角石类Ｅｒｉｄｉｔｅｓｕｎｄｕｌａｔｕｍ的体管沉积及气室沉积微细构造特征，体管沉积内部有机质层及矿物晶体层形态及厚度较稳定。气室沉积中有机质层及矿物晶体层形态及厚度变化大，晶体层内部具有柱状晶体。基于内部微细构造特征，推测体管沉积由软体上皮细胞直接分泌而成，气室沉积由体液渗透连接环在气室内表面上形成矿化基质后通过有机质层及矿物晶体层不断加积而成。另外，通过与石炭纪其它假直角石类内部沉积微细构造特征的比较，认为假直角石类内部沉积的微细构造特征不具有分类学意义。

MICROSTRUCTURE OF THE SIPHONAL AND CAMERAL DEPOSITS IN ERIDITES UNDULATUM (CEPHALOPODS)

Microstructures of the siphonal and cameral deposits in a well preserved Telychian nautiloid Eridites undulatum collected from Guizhou are studied through thin sections under a polarization microscope and etched,polished sections under a scanning electron microscope.Organic sheets and layers of mineral crystals,whose form and thickness are stable,are found in the siphonal deposits.Two layers overlap alternatively with growth of the siphonal deposits.Organic sheets and layers of mineral crystals of the cameral deposits are irregular in form and thickness,prismatic crystals can be seen in the layers of mineral crystals.Based on the microstructural characteristics,it has been suggested that the siphonal deposits may have been precipitated directly by the epithelial cells of the soft body,and the cameral deposits could have been produced by body fluids which penetrated into the connecting rings and resulted in the formation of an organic membrane that made the organic sheets and crystal layers deposit successively in the camerae.Furthermore,through the comparison with the microstructural features of the siphonal and cameral deposits of Carboniferous pseudorthocerids,the microstructural characteristics of pseudorthoceroids may not be used as a valid taxonomical criterion.