38 FLOEA OF LOWER COAL MEASUEES OF MISSOUEI. 



Sphenopteris Lacoei D. W. 



PI. XII, Fig. 3. 



1893. 8phenopterts Lacoei D. White, Bull. U. S. Geol. Surv., Xo. 98, p. 56, pi. ii., figs. 5, 6. 



Fronds quadi-ipinnate, spreading; primary pinnje broad, at right angles 

 or somewhat obhqiie to the rachis; primary rachis finely striated, flat, or 

 slighth' arched, naked; secondary pinnae alternate, close, often somewhat 

 o-\-erlapping, oblique above, at right angles in the middle and curving 

 backward below, slender, linear-lanceolate, acute, slightly contracted toward 

 the base, nearly straight or gently flexuous and curving, simply pinnate, or 

 pinnatifid below, the largest divisions being developed as ultimate pinnae, 

 with the same relations to the secondary pinnae as those of the latter to the 

 primar}^ pinnse; secondary rachis rather narrow, slightly flexuous to corre- 

 spond to the position of the pinnules, and bordered, at least in the upper 

 part, h\ a very narrow lamina decurring from the pinnules; pinnules cori- 

 aceous, dull, flat, alternate, at right angles to the rachis below, oblique 

 above, close, sometimes contiguous, or overlapping, usually with a decurrent 

 attachment to the rachis, cordate-ovate, or somewhat querciform, slightly 

 obtuse at the apex, alternately lobed, more or less constricted at the base, 

 especially on the distal side, the blade connate by a naiTOw decurrent 

 lamina; the larger pinnules, about 6 mm. long, 3 mm. wide, constricted at 

 the base so as frequently to appear pedicellate, the smaller ones above 

 becoming sessile by the slightly contracted base; lobes in the lower part 

 of the larger pinnules diAdded to near the midrib, larger than those above, 

 more or less distinctly cuneate toward the base, or rhomboidally rounded 

 or rounded-truncate at the broad top, slightly separated by a narrow, decur- 

 rent, rounded sinus, becoming in passing upward more connate and obovate, 

 smaller, more united, and more obtusely rounded, gradually passing into 

 the small indistinct terminal pinnule ; lobes of the pinnatifid pinnules 

 broadening, becoming more distant, more pointed and crenate, sessile by 

 the slightly contracting base, then lobate, and finally full-developed pinnules ; 

 primary nerves strong, sonaewhat decurrent, especially in the upper part of 

 the pinnfe, though often appearing slightly inclined or at right angles to the 

 rachis in the lower part, sometimes appearing- as a short pedicel; nervation 

 obscure, a in-imary nerve passing into each lobe, and emitting nervils that 



