FEENS— TRIPHYLL0PTEEIDEJ5— MARIOPTERIS. 33 



of the stratigraphic changes of the flioras in the Coal Measures system of 

 the central portion of the Appalachian trough lead me to conclude that M. 

 S23henopteroides is closer to M. nervosa than to any other species, both forms, 

 between which there are intermediate stages, having been developed from 

 a polymorphous earlier stock generally referred to Mariopteris muricata 

 (restricted) or Pseudopecopteris muricata as determined by Lesquereux. 



Tlie illustrations of M. sphcnopterokles given by Zeiller in his beautiful 

 work on the Flora of the Valenciennes Basin ^ appear to me as somewhat 

 doubtfully referable to this species, being in some respects closer to the 

 form commonl}' identified in the United States as Pseiidopecopteris nervosa 

 (Brongn.) Lx. From his figures and detailed drawing-s it would seem that 

 the pinna; are more obtusely pointed, instead of being spinous, the pinnules 

 being- emarginate or crenulate, not deeply dentate or dentate- spinous, and 

 the nerves less distant, coarse, or irregular than in the American form. The 

 characteristic facies of the pinna; of the latter, and even the nervation, 

 which is relatively more distant and irregular than in M. nervosa, or stronger 

 than in M. latifolia or M. acuta, are shown in the photographs, PL X, or the 

 enlargement, PI. IX, Fig. la. 



Mariopteris sphenopteroides has been found in the western coal region 

 of Arkansas and in the Lower Productive Coal Measures (XIII) at Mazon 

 Creek, Illinois, and near Coalburg, "West Virginia; and it thus far seems to 

 be characteristic of a limited zone near the base of the Lower Coal Meas- 

 ures, or Alleghany series. 



Localities. — Frequent at Owens's coal bank, U. S. Nat. Mus., 5532, 

 5707-5711; also at Gilkerson's Ford, U. S. Nat. Mus., 5533; Pitcher's coal 

 bank, U. S. Nat. Mus., 5584 (!). 



Mariopteris, sp. 

 PI. IX, Fig. 3. 



A few small fragments found among the collections represent a phase 

 of a new species generally limited to the upper part of the Potlsville series 

 in the American Coal Measures. This form, being exceedingly rare in the 

 Alleghany series of Missouri, is not present in sufficient material from this 



'Fl. fo3s. basin houill. Valenciennes, Atlas, 1886, pi. xix, figs. 3,4; text (1888), p. 171. 

 MON XXXVII 3 



