COMPARISONS WITH FLORAS OF COIv'TINENTAL EUROPE. 299 



Hoenmghausii, Mariopteris muricata, Pecopteris aspera, F. dentata, Alethopteris 

 lonchitica, Neuropteris Schlehani, Lepidodendron Veitheinm, Botlirodendron 

 pundatum, and Sigillaria elegans} This zone is presumably next above the 

 Millstone grit, 2. The middle zone, or zone of Anzin-Meurchin, is divisible 

 on paleobotanic lines into three horizons, of which the lower is character- 

 ized by the great abundance of Splienopteris {Pseudopecopteris) trifoliolaia, 

 Biplothmema {Splienopteris) fiircatum, Alethopteris Davreiixii, Sphemphyllum 

 mi/riopihyllum, and Sigillaria rugosa, as well as rarer specimens of Splienop- 

 teris (Pseudopecopteris) obtusiloha, Pecopteris abbreviata, Asteropliyllites equi- 

 setiformis, Sigillaria l(Bvigata, and Cordaites horassifoVms ; the middle horizon 

 by the continuation of Splienopteris Hoeninghausii, Alethopteris lonchitica, 

 Botlirodendron punctatum, and the rare appearance of Alethopteris valida, 

 A. Serlii, and Sigillaria camptotcenia, while the third horizon is marked by 

 the excessive rarity of the species typical of the lower zone, the absence 

 of the Stephanian species found in the upper zone, and the abundance of 

 Pecopteris abbreviata. 3. The third or upper zone, that of Bully-Grenay, 

 in the Franco-Belgian Basin, includes among its typical species the Splie- 

 nopteris {Pseudopecopteris) obtusiloba, S. neuropteroides, Pecopteris abbreviata, 

 Alethopteris Serlii, Neuropteris rarinervis, N. tenuifolia, Linopteris Suh- 

 Brongniartii (near to L. obliqua Bunb.), Asteroplujllites equisetiformis, Splie- 

 nophyllimi emarginatum, Sigillaria tessellata, S. camptotcenia, and Cordaites 

 borassifolius in abundance, and the first examples of the Stephanian types, 

 Alethopteris Grandini, Anmdaria spliemphylloides, A. stellata, Pecopteris crenu- 

 lata, and Linopteris Miinsteri, while the characteristic species of the lower 

 zone are entirely wanting. 



The reader will already have recognized the names of the common 

 American species in this upper zone, which belongs to the upper portion of 

 the "Westphalian" group.' The Westphahan {HouUler Moyen) is succeeded 

 in. the stratigraphic column of Europe by the Stephanian, on which rest the 

 Autunian and other Permian subdivisions. 



The relation of our flora to the European series is, however, somewhat 

 concisely represented by the accoiupanying condensed tabulation of the 



' In this discussion no attention wiU be paid to tlie horizons or minor geologic subdivisions of 

 ■which the yarious species are characteristic or at which their distribution begins or ends. These 

 features, which have been Tvorlied out with brilliant results by M. Zeiller, are too detailed to warrant 

 consideration in an intercontinental comparison. 



-It seems possible that the Valenciennes series may hardly extend to the top of the Westphalian. 



