FERNS— MEGALOPTERIDE^—NEUROPTEEIS. 129 



has been supposed. My studies, during- several years, of the floras of the 

 Devonian and older Carboniferous, particularly the fossil plants of the 

 Pottsville series,^ reveal so close a relationship and so great a proportion of 

 identical species at once in tlie latter series and in the "fern ledges" about 

 St. Jolm, New Bi-unswick, the only locality of supposed Devonian age at 

 which Megalopteris has been found, as to leave no room for doubt as to the 

 Carboniferous age of the St. John plant beds. On the other hand, repre- 

 sentatives of other characteristically Carboniferous genera so common in 

 the beds at St. John, such as Neuropteris, Alethopteris, Odontopteris, and 

 Pecopteris, which make the flora of that locality so unique and unparalleled 

 among the floras of other Devonian localities, have never been discovered 

 at any other Devonian locality. Typical forms of Megalopteris have been 

 collected at a number of points in the Potts\'ille series of the Appalachian 

 trough from Tennessee northward. The exceedingly strong affinity of some 

 of these with the St. John type is but an illusti'ation of the common char- 

 acter and intimate general relationship of the associated Pottsville flora 

 and that at St. John, a relationship so close as not only to render it certain 

 that the latter is Carboniferous in age, but also indicate that it may well be 

 late in the Lower Carboniferous, if not even coexistent with some of its 

 Pottsville representatives. Megalopteris, while possibly less ancient than 

 certain of the eai'ly Callipteridioid Neuropteris species, may, nevertheless, be 

 taken as an example of the archaic composite type of Neuro-Alethopteroid 

 fern life. 



In connection with the subject of the genetic relationship of this group 

 it may be remarked that Potoni(i- has proposed to include the forms with 

 mixed characters of Neuropteris and Odontopteris — i. e., those forms in which 

 some Neuropteris pinnules are found on the same plant with a greater num- 

 ber of Odontopteris pinnules — in a distinct genus, Neurodontopteris, which is 

 largely identical with the Mixoneura of Weiss. Still more recently SterzeP 

 proposed the genus Neurocallipteris for those Neuropteroid species in which 

 the pinnules of the upper portions have the Callipteroid nervation predomi- 

 nating while the basal pinnules of the pinnse have the nervation of the true 

 Neuroj^teris. 



' Equivalent in part to the Millstone grit. 

 - Flora d. Eothl. Thiiringen, 1893, p. 124. 



3 Fl. Rotlil. Oppenau ; Mitth. Grossberz. Badiseheu Geol. Landesanst., vol. iii, 2, 1895, p. 283. 

 MON XXXVII f> 



