814 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



Carboniferous to the Permian, while more recently it has come to include species 

 from the Mesozoic and even from the early Tertiary. It is therefore found 

 that through a well denned series of related specific types, the genus, which is 

 recognized as a very old one, is directly connected with existing types to be 

 found in the Gleicheniaceas, and particularly in the genus Gleichenia, as already 

 shown by Potonie, who nevertheless retains Brongniart's original name 

 (54, 53). The former practice of adopting one name for fossils and another 

 for recent forms when the two are recognized to have generic identity does not 

 rest upon a sound basis, nor is it conducive to that nomenclatural simplification 

 whicb is a great desideratum at the present time. It rather tends to perpetuate 

 and emphasize the ancient idea of the radical difference between extinct and 

 existing types, instead of directing attention toward a progressive development 

 of related forms. There is, therefore, no real reason why the genus Pecopteris 

 should not be known in the future as Gleichenia, to which the various species 

 in reality belong, and our future practice will conform to this view, in accordance 

 with that already instituted by Heer in 1875, (35: III., p. 44, pi. iv., v., vi., vii.), 

 who relegates to that genus all species of the type represented by the present 

 specimen. 



In endeavoring to institute comparison with other specimens from nearly 

 related horizons, it appears that no -representative of this plant is to be found 

 In the collections of the Peter Bedpath Museum, where the most recent horizon 

 in which any Pecopteris appears is the Upper Cretaceous. A specimen to which 

 no specific name has been assigned, was collected by Dr. G. M. Dawson, from 

 the Upper Cretaceous of Baynes Sound, B.C. This may possibly be the same 

 as a species which Sir William Dawson recognized (8) in the material collected 

 by Mr. James Bichardson, from Hornby Island, B.C., in 1872, and which he 

 regarded as closely approaching P. phillipsi of the English Oolite, but to which 

 he gave no name on account of the absence of venation. 



Dawson (5) has shown that Pecopteris browniana, Dunker, occurs in the 

 Kootanie Series, and, as originally noted by Newberry (44), it also occurs at 

 Great Falls, Montana; but since this species has now been definitely transferred 

 to the genus Cyathites, it is excluded from further consideration. Of the thirteen 

 species of Pecopteris enumerated by Knowlton (37), all except one may be 

 readily excluded from the present case by reason of their marked differences 

 in the character of the foliage. 



Upon comparison with the European forms recorded by Brongniart (4), 

 a very striking resemblance is observed to exist between our present specimens 

 and P. arborescens. This latter is characterized by having 'Pinnae, 7 cm. long 

 and 6 mm. broad at the base, at first linear but then gradually and uniformly 

 tapering toward the apex from above the middle; pinnules, 3 mm. x 1-5 mm.' 

 While a careful comparison of the two specimens shows a remarkable resem- 

 blance, it is to be noted that the one now under special consideration is much 

 the larger, a feature which constitutes the ehief and most essential difference. 

 Eurthermore, P. arborescens is a Carboniferous type from St. Etienne, and 

 1 am not aware that it has been definitely observed in any later formation. 



