FERNS— TRIPHYLLOPTEKIDE^E—MARIOPTEKIS. 3 1 



forms; thus M. muricata is very highly differentiated in, and is confined 

 almost exclusively to, the Pottsville series, while M. nervosa is character- 

 istic of the Alleghany series, seldom being found within, and near the top, 

 of the Pottsville series. The relations of the muricata and nervosa types 

 have been more fully discussed by the writer in the report on the fossil 

 plants from the McAlester, Indian Territory, coal field/ 



The form in hand is not to be confused with the one that I have com- 

 pared with M. muricata. The latter is most intimately related to a form 

 from the upper part of the Potts-\dlle series. 



Locality. — Henry County, Missouri. Received from Dr. J. H. Britts, 

 Clinton, Missouri. Precise locality unknown. U. S. Nat. Mus., 5459 



Mariopteris sphenopteroides (Lx.) Zeill. 



PI. IX, Figs. 1,2; PI. X. 



1879. Odontopteris sphenopteroides Lesquereus, Goal Flora, Atlas, p. 4, -p\. xxi, flgs. 3, 



4; text, vol. i (1880), p. 139. 

 1881. Alethopteris nervosa (Brongn.) Goepp., Achepohl, Niederrli.-Westfal. Steink., 



p. 42 (pi. xi, fig. 16?) 

 1883. Sphenopteris nohilis Achepohl, Niederrh.-Westfal. Steink., Brganzuugsbl.. iii, 



fig. 5. 

 1886. Mariopteris sphenopteroides (Lx.) Zeiller, Fl. foss. houill. Valeueieunes, Atlas, i)l. 

 xix, flgs. 3, 4; text (1888), p. 171. 



Fronds quadripinnate, dichotomous, spreading, with a somewhat flexu- 

 ous rachis ; secondary (? ) pinnse alternate, oblong-triangular, acute ; tertiary 

 (f ) pinnae alternate, open, triangular-lanceolate, tapering to an acute point or 

 spine; rachis flexuous to correspond to the pinnation, canaliculate above, 

 terete beneath, finely obscurely striate, with a narrow border; ultimate 

 pinnse open, nearly at rig'ht angles below, more oblique above, close, gen- 

 erally slightly overlapping, alternate, oblong-lanceolate, rather acute, 

 usually terminating in a short sjiine; pinnules alternate, more or less open, 

 generally touching when fully developed, or even overlapping a little, 

 ovate-deltoid, somewhat constricted at the base, more or less deeply divided 

 into lobes or teeth, decurrent to border the usually slightly flexuous rachis, 

 the lower pair on each pinna polymorphous and compound, especially the 

 proximal one, which, in the lower pinnse, is once or twice divided in the man- 

 ner characteristic of the genus; lobes or teeth deltoid, obtuse, inclined 



'Ann. Kept. U. S. Geol. Surv., vol. xix, pt. 3, p. 475. 



