62 MESOZOIC FLORAS OF UNITED STATES. 



1838. PolysticJiites Murrayana (Brongn.) Presl in Sternberg: Flora der Vorwelt, 



Vol. II, p. 117. 

 1849. Coniopteris Murrayana Brongn.: Tableau, p. 26. 

 18.56. Hy me.no fhyUites J/wrraya^ia' (Brongn.) Zign.: Fl. Foss. Form. Oolith., Vol. 



I, p. 92. 

 1865. Sphenopteris Murrayana (Brongn.) Zign. : Osserv. sulle Felci Foss. dell'Oolite, 



p. 20. 

 1876. Thyrsopteris Murrayana (Brongn.) Heer: Fl. Foss. Arct., Vol. IV, Pt. II 



(Jura-Fl. Ostsibiriens) , p. 30, pi. i, figs. 4, 4b, 4c; pi. ii, figs. 1, 2a, 3 (left 



side of fig.), 4, 4b; pi. viii, fig. lib. 



There are among the Oregon fossils certain imprints that have the 

 aspect of Sphenopteris. They are mostly small and very poorly pre- 

 served, so that their true character can not always be made out. The 

 leaf texture seems to have been very thin, so that the imprints of the 

 pinnules are generally faint. The forms agree very well with the fern 

 described by Heer as Thyrsopteris Murrayana," and I identify' the plant 

 with that species. The pinnules are narrowed at base very much, so 

 as to give them a marked sphenopterid habit. Above the narrowed 

 base the larger ones are oval or oblong, with obtuse lobes or teeth that 

 are very obliquely placed. The nerves of these were not seen. The 

 smaller pinnules, from higher up on the compound pinna, are subrhom- 

 boid or subtriangular, with crenate or undulate margins. Their nerves 

 consist of a fiexuous midnerve sending off mostly single nerves. The 

 lower anterior one may be forked. No fructification was found. 



PI. VIII, Fig. 4, gives the terminal portion of an ultimate pinna 

 from probabl}^ low down on the compound pinna, carrying the larger 

 sized pinnules. Figs. 5 and 6 show magnified pinnules of this. Fig. 7 

 represents the largest specimen found. It shows the rachis quite well, 

 but the pinnules are indistinct. Fig. 8 is an enlarged portion of Fig. 7. 

 Fig. 9 shows fragments of ultimate pinnae, probably from high' up on 

 the compound pinna, and Figs. 10 and 11 two enlarged pinnules. 

 This plant is quite variable in the form of its pinnules, if indeed all the 

 specimens show forms belonging to the same species. In some cases 

 a portion of the pinnules resembles the lower pinnules of Heer's 

 Dicksonia arctica,'' with undulate margins. Others could be selected 

 that resemble more the pinnules of Thyrsopteris Maakiana " of the same 



oFl. Foss. Arct., Vol. IV, Pt. 11, pp. 30-31, pi. ii, figs. 1-4. 



6 Op. cit., Vol. V, Pt. II (Beitr. z. Foss. Fl. Sibiriens), pp. 12-13, pi. iii, figs. 1-7. 



cQp. cit., Vol. IV, Pt. II, pp. 31-32, pi. i, figs. 1-3; pi. ii, figs. 5, 6. 



