【摘要】 <正> Sinograptus一属是穆恩之(1957)建立的,产于浙江常山大坞的下奥陶统宁国组Amplexograptus confertus带。笔者近年来在浙江江山黄泥岗村相同层位中采到不少完整的Sinograptus的标本,其中有一个Sinograptus typicalis的黄铁矿化标本,通过电子探针二次电子图象的分析和检查,对其胞管有一些新发现,为此,笔者予以补充描述。北京铀矿地质研究所刘济民同志协助摄制电子探针显微分析仪二次电子图象,陈旭同志代写英文摘要,在此谨致谢意。更多还原

【Abstract】 The present paper expresses same new ideas on Sinograptus typicalis Mu, the type species of Sinograptus defined by Mu En-zhi (1957), through an SEM study of its thecal morphology. All the materials under SEM study were collected from the Didymograptus ellesce subzone (Lower Llanvirn) of Huangnigang, Jiangshan County, Zhejiang, showing that: 1. The extending directions of the stipe and dorsal or ventral folds of the theca are not identical with each other; 2. The theca curves for 7 times and reduces for 3 times; 3. The thecal apertures all occur on one side of the stipe, looking like a crevice with transverse expansion at the upper part.Relations between the thecae (with dorsal and ventral folds) and the stipe are shown in Fig. 2. Based on this pattern, the thecal aperture has been restricted within a very narrow canal between two, neighbouring ventral folds. Therefore, the ventral fold seems to play the role of a protecting wall and making a peaceful excavation for the graptolite animal. The feeding currents should pass through a complicate way in the excavation, but it was just in this case the graptolite animal might easilyavoid the natural enemy.The writers agree with Jackson’s opinion that "It is well known that planktonie protists living in warm waters today are more spinose than coler water forms and it is tempting to draw analogies in the graptolites." According to Jackson (1976), "Holmograptus spinosus (Ruedemann), Sinograptus typicalis Mu and Paraglossograptus tentaculatus (J. Hall) of Llnvirn age illustrate spinose stenothermal species which were confined to tropical waters" (Jackson, 1978, p. 122). Sinograptus was restricted only within western Zhejiang, Southern Anhui and north-eastern Jiangxi Provinces, but in recent years, it also has been found from W. Canada, indicating that Sinograptus is an endemic genus with a less adaptation, which, however, also may be connected with the nature and depth of the sea, and the associated faunas.更多还原