中文摘要：

作者系统描述了新疆阿克苏一乌什地区下寒武统玉尔吐斯组中上部单壳类软体动物化石10属10种，其中包括3个新种、3个老种和4个未定种，它们是 Shabaktiella multiformis sp. nov. , Ilsanella acuta sp. nov. , Xian f engella yuertusiensis sp. nov. , Parcaconus xinjiangensis , Protostenotheca xinjiangensis , Aldanella attleborensis, Obtusoconus sp. , Yochelcionella sp. , Bemella sp. 和 Mellopegma sp,。上述10个属种基本上代表了玉尔吐斯组单壳类软体动物的面貌特征。文中介绍了本研究区10个属和属级以上分类系统在国际学术界的意见分歧后，重申了以壳的对称性和有无肌痕确定纲级界线的最佳分类原则，提出了应用壳型划分目级分类单元和口缘形状、壳顶与口缘的相对位置划分科级分类单元的可行性和有效性，但是不能接受把所有单板状软体动物化石通常被归入单板纲的做法，因为寒武纪早期一些单板状软体动物化石不一定符合单板纲的真实含义。文中还回顾了近二十年来建立的始单板纲（Eomonoplacophora）（Missarzhevsky，1989），太阳女神螺纲（Helcionelloida），背壳肌纲（Tergomya）（Peel，1991a＇b）和似腹足纲（Paragastr。poda）（Linsley8LKier，1984）等纲级的新概念。还有一些早期软体动物专家将许多单板状（包括帽状和螺旋状）化石归入单板纲（Runnegar et al．，1976，1985），而另有一些中青年软体动物专家继承传统理念，将它们归入了腹足纲（Parkhaev in Alexander et al．，2001）。钱逸和本格森将早期单壳类软体动物化石分成了五大形态类别，未确定科级以上分类单元名称（Qian＆Bengtson，1989）。总之，目前纲级分类单元界线不清，目级以下分类单元十分混乱，在没有全面清理早期单壳类软体动物百余个属和属级以上分类单元之前，是难以统一本文研究的早期单壳类软体动物10个属和属级以上分类系统。

英文摘要：

This paper describes univalved mollusc fossils from the upper part of the Yuertusi Formation of the Early Cambrian at Aksu-Wushi region, Xinjiang. The fossils comprise 10 genera and 10 species, including 3 new species, 3 known species and 4 undetermined species. These species are Shabaletiella multiformis sp. nov. , Ilsanella acuta sp. nov. , Xianfengella yuertusiensis sp. nov. , Parcaconus xinjiangensis, Protostenotheca xinjiangensis, Aldanella attleborensis, Obtusoconus sp. , Yochelcionella sp. , Bernella sp. , Mellopegma sp. These 10 genera and species basically reflect the aspect of univalved molluscs of the Yuertusi Formation. After introducing different opinions on classification, this paper preferrs to determine Class＇ partition based on symmetrical characteristic and muscle, and proposes to divide Order according to shell morphology and to partition Family based on aperture aspect and position between shell apex and aperture. This paper cannot accept the idea of ascribing all univalves under Monoplaeophora because that some Early Cambrian univalved mollusc fossils do not belong to Monoplacophora. The present paper reviews new concepts about Class Eomonoplacophora （Missarzhevsky, 1989）, Helcionelloida, Tergomya （Peel, 1991） and Paragastropoda （Linskey and Kier, 1983）. Some early studies assigned many monoplacophoran forms （including cap or spiral forms） to Monoplacophora （Runnegar et al. , 1976, 1985） while some other younger scholars yet regarded them as Gastropoda （Parkhaev in A.lxamder et al. , 2001）. Qian and Bengtson （1989） divided early univalves into five morphological groups and did not determine classification units of Family or above family. So present division of class unit is not clear. Order or below order unit is in disorder. Before classification on more than hundred genera of early univalved mollusks is put in order, it is relatively difficult in uniting classification system of genera and above genera in this paper. We think that determining classifi