【摘要】 <正> 本文化石材料产于北京西山门头沟群及河北宣化下花园玉带山群。门头沟群是叶良辅(1920)建立的,称门头沟煤系,王竹泉、计荣森(1933)自下而上进一步划分为“下窑坡系”、“上窑坡系”及“龙门系”。杨杰(1947)在煤系下伏玄武岩之下的页岩中发现了门头沟群的植物化石,后来又将此层位名为“杏石口亚统”。如此,门头沟群包含杏石口组、玄武岩、下窑坡组、上窑坡组及龙门组,因玄武岩在南大岭地区最发更多还原

【Abstract】 The present paper deals with the florafrom the Mentougou group in the West Hillsof Beijing (Peking) and the Yudaishangroup in Xiahuayuan,Hebei.The Mentou-gou-Yudaishan flora may be attributed to theConiopteris-Phoenicopsis flora of Sze (1956),and is characterized by the following com-ponents.1) Ferns predominant:Coniopterishymenophylloides,C.tatungensis,C.burejen-sis,Eboracia lonifolia,Cladophlebis asiatics(=Cl.haiburensis) (with large-sized pinnules),Raphaelia,Clathropteris and Hausmannia.2) Ginkgophytes abundant:Ginkgo,Ginkgoites,Baiera,Sphenobaiera,Czekanow-skia and Phoenicopsis.3) Conifers well-represented:Podoza-mites,Pityophyllum and Elatocladus.4) Cycadophytes also represented:Ano-mozamites,Nilssonia,Pterophyllum andCtenis.Besides,three genera belonging to Equi-setales,Equisetites,Neoealamites and Annula-riopsis,and rare Lycoposid,Lycopodites,alsooccur.This flora may be subdivided into threeassemblages representing three horizons.Thelower assemblage contains such old forms asEquisetites with broad stems and Balera bear-ing narrow segments,while the upper as-semblage bears some new elements,such asConiopteris burejensis,Cladophlebis delica-tula,Raphaelia prinadai,Pseudocycas pecten,in addition to the wood Xenoxylon hopeienseChang (1929) and Protopiceoxylon exstinctumGothan (Mathews et Ho,1945).As to the age of the flora,we suggest thatthe lower assemblage may be referred toLower—Middle Jurassic,the middle assemblageto Middle Jurassic and the upper assemblageprobably to Middle—Upper Jurassic.更多还原