888 FLORAL ZONES OF THE POTTS VILLE FORMATION. 



Penns3'lvania. The most iiitorostino- species of this genus occurring- in 

 the Pottsville formation of Pennsylvania, Megalopterin plumom^ closely 

 resembles J/ii>^///j.yw// Hartt from the so-called middle Devonian of 

 New Brunswick. It ditfers from the latter chiefly l)y the very oblique 

 nervation. The specimens were obtained from a slope in the Upper 

 Lykens division at Yellow Springs (jap. 



Xkl'roptkkis Pocahontas sp. no v. 

 PI. CLXXXIX. Figs. 4, 4a; PI. CXCI, Figs. 5, 5a. 



Fronds large, tri- or quadri-(0 pinnate, with very broad, strongly 

 lineate, slightly flexuose rachis, which may attain a diameter of 4 cm. 

 or more; penultimate piniue generally alternate, open nearly at a 

 right angle, becoming somewhat oblique above, close, often touch- 

 ing or slightly overlapping, linear-lanceolate or linear, very slightly 

 narrowed at the base, the margins nearlv parallel in the middle por- 

 tions, tapering a little rapidly near the top to an acute apex, the ultimate 

 pinnse being followed by a few large pinnules, rapidly succeeded by a 

 narrow, l)asally sublobate, small, obtuse, inequilateral, ovate-triangular 

 terminal, the rachis being rather strong, slighth' depressed ventrally, 

 lineate, and a little flexuose near the apex; ultimate pinnae, alternate or 

 subalternate, open at a right angle below, slightly oljlique above, usually 

 slightly overlapping or touching, rarely a little distant, the smallest 

 narrowly oblong, becoming linear, 5 to 30 mm. wide, 12 to 15 mm. in 

 length, the lower small pinnte very obtuse, the more elongated being 

 rather narrowly obtuse; rachis strong, depressed, lineate, slightly 

 curved or flexuose. 



Pinnules small, slightlv polymorphous and irregular, alternate or 

 subalternate, rarely subopposite, those in the lower portion of the 

 largest pinna- or the basal pair in the small pinnse at a right angle to 

 the rachis, the others more or less oblique, usually touching or even 

 overlapping, more rarely a little distant, laterally unecjual, often ovate- 

 round when very small, the lowest pair in the very small pinntB being 

 often nearly reniform, the succeeding pinnules broadly ovate, nar- 

 rowly ovate to ovate-ol)long, round at the apex, onl}' the lowest pair 

 in the smaller pinrne, or the lower large pinnules in the large pinnje, 

 or those a little below the apex of the penultimate piiuue, constricted 

 to near the midrib, the others being less constricted, especially at the 

 proximal angle, those near the top of the large pinnse or throughout 

 thi' greiitcr })art of the small pinnse l)eing attachinl by more than one- 

 half the width, often nearly the whole width, of the piniue, after the 

 type of CalUpteridium^ the terminal being ovate or ovate-ol)long in the 

 sniallei- pinna'. lat(M-ally unecjual, subl()l)at(^ by coiifluenc*' with the last 

 piniude on one side, slightly undulate, usually obtuse or rounded at the 

 apex, the terminals of the \'erv large piiunv biMug rather inoi'iu'longated 



