PEKMIAX ELEMENTS IX THE DUNKARD FLORA 539 



on account of the small number of characteristic Permian types and the discovery, 

 in the Monongahela, of many of the species previously unknown outside of the 

 Dunkard, thus increasing the proportion of species common to the Monongahela. 

 Furthermore, more than half of the 28 Dunkard species listed as occurring in the 

 European Permian are as common or more common in the Coal Measures both in 

 Europe and in America. 



During the summer of 1902 the writer had the opportunity to examine the very 

 interesting types described in the Pennsylvania report, as well as to make collec- 

 tions at new localities and horizons in the formation. The results are a better 

 recognition on his part of a number of important forms insufficiently or poorly 

 reproduced in the report, and the discovery of several characteristic Permian species 

 not previously known in the formation. 



To summarize the evidence as to age, the plant material of correlative value as 

 yet brought to light from the Dunkard may be grouped in five categories : 



{a) Species characteristic of the Rothliegende or higher formations of the old 

 world; (6) species closely allied to Permian types ; (c) species whose habit orfacies 

 suggest a late date; {d} species of Mesozoic aspect, and [e] Coal Measures types. 



The species which may be considered as in general characteristic of the Dyas 

 include — 



Callipteris conferta Sternb. (typical), C. lyratifolia Goepp. var. coriacea (F. and 

 I. C. W.), C curreliensis Zeill., Goniopteris newberriana {= Pecopteris fceminseformis 

 (Schloth.) Sterz. var. diplazioides Zeill.), Pecopteris germari Weiss, AktJiopteris gigas 

 Gutb., Odontopleris obtusiloba Naum., Caulopteris gigantea F. and I. C. W., Equisetites 

 rugosus Schimp., Sphenophyllum fontaineanum S. A. Mill., S. tenuifolium F. and 

 I. C. W., and Sigillaria approxhnata F. and I. C. W. 



Among the forms closely allied to species from the old world Permian are — 



Odontopieris pachyderma ¥ . and I. C. W. (cf. Diplothmema ribeyroni ZeiW.), Cyrno- 

 glossa obtusifoUa F. and I. C. W., Goniopteris elliptica F. and I. C. W., Pecopteris 

 asplenioides F. and I. C W., P. rarinervis F. and I. C. ^Y. (cf. P. pinnalifida Gutb.), 

 P. schimperiana F. and I. C. W. (cf. P. bredovii), P. [Callipteridium f^ dawsonianum 

 F. and I. C. W. sp. (cf. P.fniticosa Gutb. ), P. [Callipteridium f \ odontopteroides F. and 

 I. C. W. sp. (cf. P. pseudo-bucklandJ, Andra.), Alethopteris virginiana F. and I. C. W. 

 (cf. Ccdlipteridium subelegans Pot.), Odontopferis nervosa F. and I. C. W., Odontopteris 

 n. sp. ?, and Neuropteris flexuosa var. longifolia F. and I. C. W. (probably varietally 

 referable to N. plancliardi Zeill.). 



The above list may be extended according to the amount of comparison and the 

 personal equation of the paleontologist, but evidence of this class is unreliable and 

 of subordinate value at best and will not be further considered at this time. It 

 will be noted that several of the species in this list are properly placed also in the 

 following lists. 



Considerable weight as collateral evidence may be ascribed to species which, 

 though not yet reported from any other region, are of such aspect or facies of 

 development as to strongly suggest a period of existence later than the Coal 

 Measures floras. Such forms suggestive of later date for the Dunkard are — 



Sphenopteris acrocarpa F. and I. C. W., S. hastata F. and I. C. W., S- minutisecta 

 F. and I. C. W., Cymoglossa breviloba F. and I. C. W., C. formosa F. and I. C. W., 

 Pecopteris goniopteroides F. and I. C. W., P. heericma F. and I. C. W., P. subfalcata 

 F. and I. C. W., P. merianopteroides F . and I. C. W., P. \_ Ccdlipteridium fl uniturn 



