JURASSIC FLORA OF DOUGLAS COUNTY, OREG. 61 



PL VIII, Fig. 1, shows both counterparts natural size. PL VIII, 

 Fig. 2, gives, enlarged, an upper basal pinnule, and Fig. 3 one from the 

 terminal portion of the pinna. 



Genus THYRSOPTERIS Euntze." 



Thyrsopteeis Murrayana (Brongniart) Heer.* 



PI. VIII, Figs. 4-11. 



1836. ^eco'pteris Murrayana Brongn.: Hist. Veg. Foss., p. 358, pi. cxxvi, figs. 1, 

 lA, 2-4, 4A, 5, 5A. 



a Mr. Seward very naturally doubts the occurrence in a fossil state of a monotypic genus of ferns now 

 livin", but confined to the island of Juan Fernandez, and he thinks that the Cretaceous species belong to 

 the extinct genus Onychiopsis of Yokohama and the Jurassic ones to Brongniart's Coniopteris. In the Fif- 

 teenth Annual Report of the United States Geological Survey, 189.5, pp. 383-384, I discussed this question, 

 referring to Thyrsopleris Murrayana (Brongn.) Heer from the Oolite of Yorkshire, saying: 



"Brongniart had already pointed out the resemblance of his Pecopteris Mwrayana from the Oolite of 

 Yorkshire to this living genus, and had united this species with others into a distinct genus, Coniopteris, to 

 which Saporta afterwards referred a number of species from the Jurassic of France. It is therefore very 

 probable that the genus Thyrsopteris, which is now so nearly extinct, was widely distributed over the northern 

 hemisphere in Jurassic time. We have in America no trae Jurassic flora thus far, but should such a flora 

 hereafter come to light there can scarcely be any doubt that this genus will be found in it." 



This prediction seems now to have been verified. In the Nineteenth Annual Report, Ft. II, p. 658 (foot- 

 note), the question of retaining the name was again raised. Seward and Nathorst regard all the forms as 

 belonging to extinct genera, but there is not complete harmony among paleobotanists on this point. Potonie 

 in Engler and Prantl's Nat. Pflanzenfamilien, Teil I, Abth. 4, Lief. 188, Leipzig, 1899, p. 123, says; "The 

 remains from the Jurassic of Spitzbergen, of the Amoor country, and of England, especially those figured by 

 Leckenby (1864) and Heer (1876), including Thyrsopleris Murrayana (Brongn.) Heer, and T. Maakiana 

 Heer as well in their fertile as their sterile parts, so closely resemble the recent species T. elegans that it is 

 difficult to doubt the correctness of their reference to that genus.'.' 



While, therefore, it is probable that all the fossil forms will ultimately be referred to extinct genera, 

 such genera must have closely resembled Thyrsopteris and were probably its early Jurassic and Cretaceous 

 ancestors. The present isolated species must therefore be regarded as a last remnant of a once widely dif- 

 fused "roup of ferns, and belongs to the class of waning types, like Ginkgo hiloba and the two surviving species 

 of Sequoia. The case is therefore by no means an isolated one, and becomes highly interesting to the 

 student of plant development. — L. F. W. 



''Although Mr. Seward (Jur. Fl. Yorksh. Coast, p. 100) refers Heer's plant to Coniopteris hymenophylloides , 

 Professor Fontaine sees reasons for keeping it distinct. After receiving Mr. Seward's book, 1 called his atten- 

 tion to the fact, and in a letter to me, dated August 21, 1901, he says: 



"My idea was that only those forms of Murrayana type ought to be united with Coniopteris that have 

 the proper fructification, or are closely associated with it. There is no such fructification with the Oregon 

 forms. I think that the Murrayana type of fern is the sterile form of more than one Jurassic species, and 

 It would be convenient to keep the name for any of that type whose fructification is not known, and use it 

 as the name Cladophlebis is used. This was the reason why I retained the species." 



I give therefore in the synonymy only those references that are confined to this form as found in Jurassic 

 strata — i. e., to the original Yorkshire plant and to Heer's specimens from Ust-Balei in Siberia. The Liassic 

 form Pecopteris Pingelii Schouw, Dicksonia Pingelii (Schouw) Bartholin, from the island of Bornholm, although 

 thought by Brongniart to be perhaps the same, and generally so regarded by later authors, is omitted as of 

 earlier date involving change of name, and as still somewhat doubtful, but as it has always been associated 

 with Pecopteris Murrayana and not with Sphenopteris hymenophylloides, it is also omitted from the synonymy 

 of Coniopteris hymenophylloides. — L. F. W. 



