THE BRIAN OR DEVONIAN FORESTS. 95 



The genus Fivtopteris of Sternberg, though the original species 

 (P. ptmetata) appears as a Lepidodendron in his earlier plate (Plate 

 4), and as a SigiUaria {S. punctata) in Brongniart's great work, is a 

 true tree-fern; and the structure of one species (P. Cottai) has been 

 beautifully flguered by C!orda. The species hitherto described are 

 from the Carboniferous and Permian. 



The second specimen of this species represents a lower part of 

 the stem. It is thirteen inches long and about four inches in diam- 

 eter, and is covered with a mass of flattened atrial roots lying paral- 

 lel to each other, in the manner of the Psaroniteg of the coal-forma- 

 tion and of P. Eriantis of the Upper Erian or Devonian. 



4 Astert^teris noveboracensis, gen. and sp.n. — The genus Aa- 

 teropteris is established for stems of ferns having the axial portion 

 composed of vertical radiating plates of soalariform tissue embedded 

 in parenchyma, and having the outer cylinder composed of elongated 

 cells traversed by leaf-bundles of the type of those of Zygopteris. 



The only species known to me is represented by a stem 2*5 cen- 

 timetres in diameter, slightly wrinkled and pitted externally, per- 

 haps by traces of aerial roots which have perished. The transverse 

 section shows in the centre four vertical plates of scalariform or im- 

 perfectly reticulated tissue, placed at right angles to each other, and 

 united in the middle of the stem. At a short distance from the 

 centre, each of these plates divides into two or three, so as to form 

 an axis of from ten to twelve radiating plates, with remains of cellu- 

 lar tissue filling the angular interspaces. The greatest diameter of 

 this axis is about 1*5 centimetre. Exterior to the axis the stem con- 

 sists of elongated cells, with somewhat thick walls, and more dense 

 toward the circumference. The walls of these cells present a curious 

 reticulated appearance, apparently caused by the cracking of the 

 ligneous lining in consequence of contraction in the process of car- 

 bonization. Embedded in this outer cylinder are about twelve vas- 

 cular bundles, each with a dumb-bell-shaped group of scalariform 

 vessels enclosed in a sheath of thick-walled fibres. Each bundle is 

 opposite to one of the rays of the central axis. The specimen shows 

 about two inches of the length of the stem, and is somewhat bent, 

 apparently by pressure, at one end. 



This stem is evidently that of a small tree-fern of a type, so 

 far as known to me, not before described,* and constituting a very 

 complex and symmetrical form of the group of Palaeozoic ferns allied 



* Prof. Williamson, to whom I have sent a tracing of the structure, 

 agrees with me that it is new. 



