川北早志留世似包珊瑚属的两个新种

Two Early Silurian species of Amplexoides Wang,1947 from the north of Sichuan,China

在采自四川广元和朝天一带早志留世王家湾组的材料中发现具典型包珊瑚型隔壁,发育三级隔壁的单体珊瑚新类群。该类群边缘厚结带窄,一级隔壁长,几乎可达个体中心;二、三级隔壁短,隔壁由层状组织组成,横板完整,近平列状或密集成束状,无鳞板。基本特点与似包珊瑚属(AmplexoidesWang,1947)最为接近,因而暂将该类群归入包珊瑚属,共有两个种:Amplexoides trioseptatussp.nov.,Amplexoides modaoyaensissp.nov.。根据新资料补充了似包珊瑚属的部分属征,讨论了AmplexoidesWang的主要类群、构造特点及其演化,并系统描述了两个新种。

Several specimens with incipient development tertiary septa and long, slender, amplexoid major septa are found in the materials collected from Wangjiawan Formation in Guangyuan and Chaotian in the north of Sichuan, China. The author refer these forms temporarily to Arnplexoldes Wang for the features of these specimens are closely similar to that of Arnplexoides Wang, with narrow peripheral stereozone, long, slender major septa and weakly developed minor septa; septa composing of lamellar tissue in the peripheral; tabulae flat or bunchiness, complete; no dissepiments. In this paper, two species are described, that is, Amplexoides trioseptatus sp. nov. , Arnplexoides rnodaoyaensis sp. nov.. The diagnosis of Amplexoides Wang is emended to include the new forms with tertiary septa. The affinity of the two new forms with the others similar faunus are discussed.