陕西镇巴下寒武统水井沱组小壳化石新属种

本文描述了陕西镇巴下寒武统水井沱组中的小壳化石３新属５新种。样品采自镇巴小洋坝曾家坡，共生化石有三叶虫、古介形虫、海绵骨针和大量软舌螺等。化石组合面貌表明其地质时代属筇竹寺期。另外，在峡东水井沱组中发现了微网虫（Ｍｉｃｒｏｄｉｃｔｙｏｎｓｐ．）化石骨片（图版Ｉ，图１８，１９），可与云南筇竹寺组及陕南水井沱组对比，说明Ｍｉｃｒｏｄｉｃｔｙｏｎ广泛分布于扬子地台区。

NEW SMALL SHELLY FOSSILS FROM THE LOWER CAMBRIAN SHUIJINGTUO FORMATION OF ZHENBA,SHAANXI

The new small shelly fossils described and illustrated here were collected from the Lower Cambrian Shuijingtuo Formation of Zhenba,Shaanxi,including 3 new genera and 5 new species,associated with such organisms as Trilobita,Ostracoda,sponge spicules and some uncertain taxa of sclerites.These features show that the Shuijingtuo Formation belongs to the Early Cambrian Qiongzhusi Stage in geological time.The discovery of these new small shelly fossils is of vital significance for studying the systematic evolution of post-Meishucunian small shelly fossils,and for making correct correlation with those Qiongzhusi Stage beds containing small shelly fossils inside and outside China.