心笔石的末端形态

THE SHAPE OF THE DISTAL END OF CARDIOGRAPTUS

心笔石多年以来均以“末端凹陷”为其主要特征之一 ,但后来发现有些种不存在这种凹陷。根据对大量末端保存良好的Cardiograptus的研究分析 ,笔者认为 ,“末端凹陷”并非Cardiograptus属的特征。Harris 1 91 6年最早描述的C .morsus及其它被描述为“末端凹陷”的标本大都是由于末端保存不好所至。Cardiograptus的末端形态与笔石体末端胞管发育长短及保存状况有关 ,可呈浅凹、平齐或圆突。如果两枝在末端分开 ,则应归于Oncograptus属 ,末端凹缺并非是Cardiograptus属的特征 ,也不是该属不同种之间的区别。

According to the examination of many Cardiograptus there are good distal ends of which in hundreds specimen and the analysis of the development of the graptolite stipes, the author believes that ‘distal end deeply emarginate’is not characteristic of Cardiograptus.According to Cardiograptus and Cardiograptus morsus first described by Harris (1916)and other specimens described,‘distal end deeply emarginate’mostly have losed some parts in the distal end for poor preservation. There maybe are slig...