1904.] Culm Measures of Devon, and the Age of the Beds. 97 



Sphenophijllales. 



Sphenophyllum cuneifolium (Sternb.). 

 Cycadofilices. 



Neuropteris obliqua (Brong.). 



Neuropteris Schlehani, Stur. 



Alethopteris Serli (Brong.). 



Alethopteris lonchitica (Schl.). 

 Filicales (?). 



Mariopteris muricata (Schl.). 



Urnatopteris tenella (Brong.). 



Renaultia footneri (Marrat). 



Renaultia schatzlarensis (Stur) (?). 



Megalopteris (?) sp. 

 Lycopodicdes. 



Lepidodendron aculeatum, Sternb. 



Lepidodendron obovatum, Sternb. 



Lepidodendron fusiforme, Corda. 



Lepidophloios acerosus (L. and H.). 



Sigillaria scutellata, Brong. 



Sigillaria tessellatu, Brong. 



Stigmaria faoides (Sternb.). 

 Cordaitales. 



Cordaites (Artisid) sp. 

 Incertce sedis. 



Trigonocarpus Parkinsoni, Brong. 



The opinions which have been held with regard to the age of 

 the Upper Culm Measures of Devon, and the horizons which they 

 represent, may be briefly summarised as follows : De la Beche, and 

 Sedgwick and Murchison regarded these beds, as has been already 

 stated, as the equivalents of the Upper Carboniferous in other British 

 Coal-fields, and by the year 1840 this conclusion was generally 

 accepted. There appears to have been some doubt, however, in more 

 recent times as to the exact subdivision of this great series to which 

 the Bideford beds should be referred. Townshend Hall (18661878) 

 regarded them, on lithological grounds, as the equivalents of the Mill- 

 stone Grit. Pengelly (1867), and Murchison (1872) referred them to 

 the Coal Measures, and Mr. H. B. Woodward (1887) doubtfully to the 

 Lower Coal Measures. Mr. Ussher (1888 1901) has not expressed 

 any decided views on this subject; he appears to be inclined to 

 support Hall's view that these beds are equivalent to the Millstone 

 Grit in other areas. 



We see, therefore, that previous conclusions, based on grounds 

 other than palseontological, have apparently not been put forward 

 with much confidence. 



H2 



