Abstract
The present article is based on specimens collected by Prof. YABE and Mr. K. OZAKI from the Tsinan limestone of Middle Ordovician age, west of Poshan, Shahtung, China. The Tsivan limestone is beleived to be correlated with the Chikusan bed of South Korea and the Black River-limestone of North America.
At this place I should like to offer my warmest thanks to Prof. H. YABE and Mr. K. OZAKI for kindly presenting their specimens to my study, and specially to Prof. H. YABE for making possible the publication of this short note.
