湖南慈利早志留世蛇尾纲化石的发现

本文描述和讨论了早志留世棘皮动物蛇尾类的一个新属一Ciliophiurina。它系作者采自湖南慈利下志留统龙马溪群,为我国早志留世地层中首次发现,又是我国迄今为止所获得的最古老的蛇尾纲化石。它不仅丰富了蛇尾纲化石的资料,而且对今后研究蛇尾类演化,生物地理分布等特征,也具有一定的理论意义和实用价值。

THE DISCOVERY OF NEW OPHIUROIDS IN THE LOWER SILURIAN FORM CILI, HUNAN

The new genus Ciliophiurina was collected from the Lower Silurian at Cili of Western Hunan by the writer. It was found in association with trilobite Ciliscutellum ciliensis Lin, Glyptograptus sp., crinoids and brachiopods in a bed consisting of dark grey fine sandstone and yellowish green shale. Beneath this bed were found Pristiograptus, Monograptus, Rastrites and Climacograptus. The diagnostic features of the genus are given below: The speciement of this genus shows the dosal surface, the small disc, five pairs of radial plates, a rectangular central plate and simple arms, which' sinuate and gradually tapering, extend over a distance five times the diameter of the disc and are composed of a series of plates, but it shows the absence of ventral and dorsal shields, broad and narrow lateral shield, short spines on laterals and slender vertebrae. The new genus differs from the Ophiurina Sturtz 1890 in that the latter disc has a thickened margin but no visible plates. It is distinguished from Ophiaulax Ubaghs 1941 by the fact that the former has neither dosal shields nor the margin of the disc. It differs from the Argentinaster Ruedemann 1861, in that the latter disc is larger and it has a narrower margin, larger lateral shields and a fine median suture on the vertebrae. Type species: Ciliophiurina hunanensis (gen. et sp. nov.)