144 FOSSIL PLANTS. 



served example of Megaphyton frondosum, and should be united with that 

 plant. This fern stem attained considerable size. 



The Museum of the Geological Society of London possesses a specimen 

 presented to that society by Wm. Hutton, Esq., which, though the full 

 dimensions of the stem are not shown, measures 19 inches in length and 

 8 inches in width. The scars, which stand about an inch apart, are nearly 

 3 inches wide. This, I believe, is the form which has been named Megaphyton 

 magnificum by Dawson, but which does not differ from Megaphyton frondosum, 

 except in being larger and the scars better preserved than on the type of 

 the latter species, the counterpart of which is in the Collection. 



Some fine specimens of Megaphyton are in the Natural History Museum, 

 Newcastle-on-Tyne. One of these shows on the upper end of the fossil well- 

 preserved scars, apparently representing the Megaphyton Ooldenbergi, Weiss ; 

 at the other end the less well-preserved scars represent Megaphyton approxi- 

 matum, L. and H., or Megaphyton frondosum, Artis. These three species are, I 

 believe, merely different ages and states of preservation of the same plant. 



Feistmantel figures in his Vers. d. Bohm. Kohlenab. some specimens of 

 Megaphyton. Of these he names those on pi. xx. figs. 2, 3, and pi. xxi. 

 Megaphyton giganteum, and that on pi. xx. fig. 1, Megaphyton ma/jus. All 

 these examples are apparently only old, and not very well-preserved speci- 

 mens of Megaphyton frondosum, Artis. 



Whatever Steinberg's Megaphyton giganteum (Vers. ii. p. 187, pi. xlvi.) 

 may be, whether really a Megaphyton or a decorticated Ulodendron, is a 

 point very difficult or impossible to decide, but I think Feistmantel's Mega- 

 phyton giganteum should be referred as above. It must be noted, however, 

 in regard to Feistmantel's figures of Megaphyton giganteum, that Zeiller 

 thinks them similar to the specimen he has named Megaphyton Souichi (Veget. 

 Foss. du Terr. Houil. p. 103, pi. clxx. fig. 3). I fear this last-mentioned 

 species is founded on an imperfectly preserved specimen, one not showing 

 clearly the original form of the leaf -scar, and being very much in the same 

 state of preservation as Artis's type of Megaphyton frondosum, which is 

 proved by many transitional specimens, and transitions in the form and pre- 

 servation of the frond scars on the same fossil, to be similar to Megaphyton 

 approximatum, L. and H. But though not prepared to say that Megaphyton 

 Souichi, Zeiller, belongs to Megaphyton frondosum, Artis, still I feel little 

 doubt in referring Feistmantel's figures to the last-mentioned species. 



It is evident that with the age of the plant the form of the leaf -scar would 

 alter more or less, and that the scars on the lower part of the stem, even 

 when the plant was in life, would through natural causes gradually lose the 

 sharpness of the contour possessed by those situated higher up the stem, and 

 from which the fronds had only recently fallen. Such modifications occur in 

 the frond scars on the stems of recent tree ferns, and we have every reason 

 to believe that their fossil representatives participated in the same changes. 

 When we couple with this the different appearances imparted during fossili- 

 sation, and partial decay probably taking place in some cases before the 

 stems were finally imbedded in what now forms their matrix, it is evident 

 that great care is necessary in the discrimination of such species, though at 

 the same time care must be taken not to ignore real specific differences. 



Horizon. Coal Measures. 



Locality. British. Yorkshire : Eowmarsh (counterpart of type). 



CAULOPTERIS, Lindley and Hutton, 1832. 

 Fossil Flora of Great Britain, vol. i. p. 121. 



Caulopteris peltigera, Brongniart, sp. 



Caulopteris peltigera. 



Bronn, Index Palseont. p. 252. 



Feistmantel, O., Ueber Baumfarrenreste d. Bohm.Steink. p. 13, pl.ii.fig. 2. 



