REVIEWS 197 



Zwickau basin of Saxony, the Schwadowitz beds in lower Silesia, and 

 with the Mazon Creek, Illinois, flora of the United States. 



The flora of Mazon Creek seems to find its place in the Kittanning 

 •group of the Pennsylvania basins, and probably near the horizon of 

 the Middle Kittanning coal. The presence of certain species, particu- 

 larly of Odontopteris, of abundant Linopteris obliqua, of Pecopteris Mil- 

 toni, of Alethopteris Grandini, and of Sphenophylhcm oblongifolium in the 

 Heraclean flora leads me to conclude that the Caradons material was 

 derived from beds slightly later than the Mazon Creek horizon, or 

 perhaps as high as the Freeport group, which is next above the Kittan- 

 ning group, though also within the Allegheny series. Sphenopteris Cre- 

 pini, which is probably present in the upper Kanawha group, is very 

 closely related to Sphenopteris sagittata from Mazon Creek and ,5. 

 ophioglossoides from the Des Moines series of Missouri. Sphenopteris 

 Bronni, Nevropteris tenuifolia, Sphenophyllum cuneifolium and Cardio- 

 carpus congruens are perhaps the only species whose presence in the 

 Caradons flora argues, on the one hand, for a horizon lower than that 

 of Mazon Creek. The far more important ^and abundant evidence of 

 the fern elements is, on the other hand, for a rather later date. 



The most interesting of the plants newly described from the Cara- 

 dons beds are Pecopteris Armasi and Plinthiotheca anatolica. The for- 

 mer appears to form a connecting link between Pecopteris and Callipter- 

 idiiun. Plinthiotheca is represented by thick, fleshy peltate or cyclop- 

 teroid leaves, radiately densely vascular and covered by small capsules 

 arranged in fours in contiguous squares. These capsules are regarded 

 by Professor Zeiller as sporiferous, rather than polleniferous ; and the 

 type is therefore tentatively ranged by him with the ferns instead of 

 with the Doleropteroid gymnosperms. The examination of Zeiller's 

 figures and a careful comparison of the types of Dolerophyllum penn- 

 sylvanicum in the Lacoe collection convinces me that the Heraclean 

 type is generically identical with that described from Pennsylvania by 

 the late Sir William Dawson. 1 



The generally close agreement mutually between Professor Zeiller's 

 correlations of the Heraclean floras in Europe or this country with my 

 own correlations of the Middle Pottsville, the Lower Kanawha, and the 

 Allegheny series well illustrates the marked paleobotanical differ- 

 entiation of the stages, and the regularity of the sequence, as well 

 as the extraordinary geographical distribution of the several Middle 



'Can. Rec. Sci., Vol. VI, p. 8, 1890. 



