FERNS— SPHENOPTEEIDEJS—SPHENOPTEEIS. (35 



lower inferior nerves in the pinnules near the base of the segment are found 

 to bifurcate at a variable distance from the median nerve, but the superior 

 nerves, as well as all those 'of the smaller pinnules, are undi^dded. 



In none of the specimens identified as this species have I found the 

 distinctive characters of the genus Pseudopecopteris. On the other hand, all 

 the details seem to be those of Pecopteris or Splienopteris. M. Zeiller has 

 referred this species to Pecopteris, at the same time inscribing^ Pseudopecop- 

 teris suhcremdata Lx. as a synonym of Pecopteris cremdata Brongn. It is 

 true that the specific separation, perhaps at the suggestion of Schimper," of 

 the American species, which was at first correlated with the European form, 

 was largely based on the insufficiency of Brongniart's diagnosis and illus- 

 trative material. But while many of tlie Illinois specimens appear to ha 

 referable to Brongniart's species,' so excellently as well as authentically 

 elaborated by Zeiller* after a comparison of Brongniart's original, the more 

 simple American type does not seem to me to be included therein. It is 

 also quite clearh^ different from the plant illustrated as Pecopteris cremdata 

 by PotonicV who also unites Pseudopecopteris subcremdata as a S3monym of 

 Brongniart's plant. The Thuringian specimen 'would seem to be a true 

 Pecopteris. The Old World plant seems to differ from that from Missom-i 

 by the thicker lamina and the much more open, frequently obscured nerves,- 

 which in the apparently corresponding portions are once forked, instead of 

 remaining simple. 



The oblique position of the slightly connate pinnules, the rather strongly 

 decurrent median nerve, the thin lamina, crenulate or erose above, and 

 decurring to form a marginal wing along the superior rachis between the lat- 

 eral pimise, and the relatively narrow flexuous rachis led me to temporarll}^ 

 regard the form in hand, which should, perhaps, be separated from the com- 

 mon American type, as a representative of the genus Splienopteris. It may, 

 like the Pseudopecopteris spinulosa Lx.^ to which it is related, be regarded as 

 one of the intermediate forms, so far as outline and nervation merely are 

 concerned, between Pecopteris and Splienopteris. It appears to be very 



' Fl. foss. houill. Viilenciennes, p. 192. 

 - Trait(5, vol. iii, p. 500. 



■' Hist. ve'g. foss., p. 300, pi. Ixxxvii, figs. 1, la. 

 ■■ Fl. foss. houill. Valenciennes, p. 192, pi. xxv, fi.!>8. 1-4. 

 » Fl. Kothl. Thiiringen, p. 65, pi. vi, figs. 1-4. 

 '•Coal Flora, p. 195, pi. Ivi, figs. 1, la. 

 MON XXXVII 5 



