100 MESOZOIC FLORAS OF UNITED STATES. 



Pteeophyllum ^quale (Brongniart) Nathorst. 

 PL XX. 



1825. Nilsonia ? sequalis Brongn. : Ann. Sci. Nat. Paris, Vol. IV, p. 219, pi. xli, 



fig. 6. 

 1828. PteropJiyUum dubium Brongn.: Prodrome, p. 9.5. 

 18.38. Zamites sequalis (Brongn.) Presl in Sternberg: Flora der Vorwelt, Vol. II, 



p. 198. 

 1841. Ptihphyllum sequale (Brongn.) Morr. : Ann. & Mag. Nat. Hist., Ser. I, Vol. 



VII, p. 117. 

 1878. Pterophyllum sequale (Brongn.) Nath.: Foss. Fl. vid. Bjuf, Hft. I, p. 11 



(nomen); K. Svensk. Vet.-Akad. Handl., Vol. XVI, No. 7, pp. 18, 48, 



pi. ii, fig. 13; pi. vi, figs. 8-11. 



Nathorst has given from the Rhetic of Sweden, with the name Ptero- 

 phyllum cequale," two forms that seem to me to belong to different species. 

 The plant figured in his Floran vid Bjuf, Heft II, pi. xv, fig. lla, as 

 P. cequale rectangulare seems to be identical with P. rajmahalense '' 

 from India. This I infer from the fact that the true P. cequale and P. 

 rajmahalense are both abundant in the Oregon flora, and are quite 

 constant in character, with differences sufficient to denote that they are 

 different plants. It is true that a few forms are intermediate between 

 the two, but they are exceptions, and not sufficient to establish a passage 

 of one form into the other. In plants of this type there could not be a 

 variation in the size of the leaflets without approaching the one or the 

 other type, and in the great number of specimens that were obtained they 

 are to be expected. They should be interpreted not as true passage forms, 

 but rather as aberrant and accidental. It is possible to select in the 

 many specimens a few forms that would make a passage from the largest 

 of the rajmahalense type to the most minute of the P. Nathorsti leaves. 



The leaf substance of P. cequale is thinner than that of P. rajmahalense. 

 The rachis is comparatively slender. No entire leaves were seen. The 

 leaflets are long in proportion to their width, appearing slender, and con- 

 trasting in that point with those of P. rajmahalense. They are linear, 

 with the margins parallel to each other, and are mostly slightly falcate. 



"Floran vid Hoganiis, p. 18, pi. ii, fig. 13, pp. 48-49, pi. vi, figs. 8-11; Floran vid Bjuf, pp. 67-68, pi. 

 XV, figs. 6-10. 



''Oldham and Morris, Foss. FI. of the Rajmahal Series, p. 25 (Fbss. Fl. Gondw. Syst.,Vol. I), pi. xiii, 

 figs. 3, 4, 5; pi. xiv, fig. 2; pi. xviii, fig. 2. 



