A series (421.3–416 Ma ago) of the Silurian of N. America equivalent to the Lower Ludlow to terminal Pridoli, preceded by the Gorstian, followed by the Lochkovian.
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。