中文摘要：

本文利用光学显微镜（ZEISS Imager A2）和扫描电子显微镜（日立S-4800）对大兴安岭双壳缝目7种硅藻植物进行观察,包括膨胀桥弯藻Cymbella tumida（Gregory）Cleve、线形弯肋藻Cymbopleura linearis（Foged）Krammer、窄异极藻Gomphonema angustatum（Kützing）Rabenhorst、隐头舟形藻Navicula cryptocephala Kützing、双头辐节藻Stauroneis anceps Ehrenberg、普通肋缝藻Frustulia vulagris Thwait和细纹长蓖藻Neidiumaffine（Ehrenberg）Pfitzer,对这些种类的形态特征进行了研究,初步探讨了这些种类之间的形态差异。为大兴安岭藻类资源调查提供了基础资料。

英文摘要：

Diatoms,as a major group of autotrophic and eukaryotic algae,is one of the most common phytoplank-ton found in almost every aquatic habitat. In 2014,100 samples were collected from Great Xing＇an Mts. In this paper,seven species of Biraphidinales（ Bacillariophyta） were reported. Morphological characters of each of them were observed by LM and SEM,and description of the morphological character and distribution habitat were given in this paper. The seven species and their typical features are as follow：（ 1） Cymbella tumida（ Gregory） Cleve： the central area has a stigma and the valve at the end has the pore field;（ 2） Cymbopleura linearis（ Foged） Krammer： the central area has the central nodule,silica ridge between the areolae and valve at the end has helictoglossa;（ 3） Gomphonema angustatum（ Kützing） Rabenhorst： the valve at the end has the pore field;（ 4） Navicula cryptocephala Kützing： terminal raphe end present strong hook shape;（ 5） Stauroneis anceps Ehrenberg： central area has the stauros;（ 6） Frustulia vulagris Thwait： the valve at the end has helictoglossa;（ 7） Neidium affine（ Ehrenberg） Pfitzer： terminal raphe end present ＂Y＂shape. These seven species belong to Cymbellaceae,Gomphonemaceae and Naviculaceae.