58 FLOEA OP LOWER GOAL MEASURES OF MISSOURI. 



may be broken or buried in tlie matrix so as to present a somewhat similar 

 outline. 



LocaJltij. — Near Clinton, Henry Countv Missouri ; precise locality 

 unknown; U. S. Nat. Mus., 5662. 



SPHENOPTEEIS ILLINOISENSIS 11. Sp. 



PL XIX, Fig. i; PI. XLIV, Fig. 1. 



1870. Alethopteris liymenophylloides Lesquereux, Kept. Geol. Surv. Illinois, vol. iv, 



p. 393, pi. X, figs. 3, 3, 4 (uou fig. 1). 

 1S74. Alethopteris hymenophyUoldes Lx., Scblmper, Traite, vol. iii, p. 500. 



1878. Alethopteris hyineiiophyUoides Lx., Andrews, Elem. Geol., p. 177, fig. 323. 



1879. Pseudopecopteris liymenophylloides Lesquereux, Coal Flora, Atlas, p. 10, pi. Ivi, 



figs. 3, ^or-h (non fig. 2); text, vol. i (1880), p. 196 (pars). 



Fronds tri- or poly-('?) pinnate, lax, rather delicate; form of primary 

 pinnse not sufficiently known for description; secondary (?) pinnte oblong- 

 lanceolate, or lanceolate, acute, rather dense though delicate, the rachis being 

 rather sleiider, finely lineate, rounded beneath, shallowly canaliculate on 

 the upper side, with narrow thread-like central strand in relief on the back, 

 giving off thread-like branches for the pinnae of the next order, and bor- 

 dered by a wide lamina; ultimate pinnse alternate, oblong-lanceolate or 

 oblong-triangular, broadest at the base, rather blunt pointed, open or some- 

 what oblique, close, usually slightly overlap2Ding, provided with simple or 

 pinnatifid pinnules in the lower portion, becoming pinnatifid, and crenulate- 

 lobate by the confluence of the pinnules near the top, and joined at the base 

 of the decurrent lamina; rachis of the ultimate pinnfe thread-like, terete on 

 the back, nearly straight and often decurrent at the base to meet the supe- 

 rior rachis at a very narrow angle; pinnules alternate, oblique, usually at 

 an angle of nearly 45° of divergence from the rachis, close, usually touch- 

 ing- or slightly overlapping, generally curving slig-htly upward, either when 

 small, short, oblong, 2-2.5 mm. long, .75-1.5 mm. wide, obtuse or obtusely 

 pointed at the top, connate up to near the middle, or, when larger, becoming 

 ovate and oblong-ovate, obtuse, and developing at first 1 to 3 very erect, 

 narrow, obtuse teeth above the middle, later bearing 4 to 6 short broad 

 teeth, and, becoming cut into 6 to 9 longer obtuse teeth, soon passing the 

 lobate stage into pinnules, the lower pair of which are usually quite oblique, 

 although the lowest inferior pinnule is sometimes heteromorphous ; lamina 



