302 FLORA OF LOWER COAL MEASURES OF MISSOUEL 



But although the ideutieal species coincide so nearly exactly in their 

 occurrence in the upper zone, we may profitably inquire as to the relations 

 of the Missouri flora to that of higher beds not represented in this field, and 

 therefore not tabulated, or whether, while the main body of our flora is 

 most closely allied to the zone of Bully-Grenay, the flora as a whole is not 

 more closely bound to the succeeding floras or those of the lower zone. 



The testimony of the related species recorded in the table, so far as it 

 concerns this inquir}-, would seem to indicate less strongly the similarity of 

 our flora to that of the upper zone, although nearly the same ratio prevails 

 in the distribution in the middle zone. As tending, however, to explain this, 

 it should be stated that in a few cases the species from the Valenciennes Basin, 

 tabulated for the comparison, are not really so intimately bound in their 

 specific details to the corresponding Missouri plants as are other Stephanian 

 species not occurring in the Valenciennes series. Thus Splienopteris Van 

 Ingeni is probably most closely related to Sphenopteris Matlieti from the Com- 

 mentry Basin (Stephanian), Pecopteris Jenneyi to P. densifolia or P. oreopteridia 

 of the same group, while Lepidostrohiis princeps is much nearer L. Goldenbergii 

 than to L. Geinitsii, used for comparison with the Valenciennes flora. 



But besides the evidence of related species, Avhich is after all of very 

 subordinate weight, we have in the material from Henry County a number 

 of species of Stephanian identity or affinity. Among the former are Spihe- 

 nopteris cristata, 8. suhcremdata, Pecopteris hemitelioides ? , and P. Candolliana 

 and P. cf. arhorescens, while Splienopteris climropliyUoides is regarded as essen- 

 tially a Stephanian species. Still other types are more modern in their 

 characters or generic occurrence. Examples of these are possibly present 

 in Brittsia, which is perhaps related to the Stephanian genus Zygopteris, and 

 in the plants provisionall}^ referred to TitanophyUiim and Dicranojihyllum, both 

 genera of the Stephanian, or in CaUipteridiwn Sullivantii, perhaps most nearly 

 related to Odontopteris obtusa, Sphenophylluin Lescurianum, which seems to 

 belong to the later group represented by 8. angustifolium, etc. ; the Rhahdo- 

 carpus Mansfieldi, which is undoubtedly ver}^ closely allied to Pachytesta 

 insignis of the higher Measui-es, and perhaps the Tceniopteris missouriensis. 



The presence of these later types in the flora of Henry County,^ as 



' Of the 26 species represeuted in both the Missouri and Valenciennes floras, only 1, Lepidodendron 

 rimosum, is lacking in the upper (Bully-Grenay) zone. This species was found only in the lower 

 horizon of the middle zone of the Franco-Belgian Basin. 



