NO. 2158. JURASSIC FLORA FROM ALASKA— KNOWLTON. 455 



established by Lindley and Hutton ^ in 1834, with D. rugosum from 

 the Lower Oolite of Yorkshire, England, as the type-species. ^ 



Since that time about 40 species have been established, among 

 them the splendid species with which the Matanuska specimens are 

 beMeved to be identical. According to Nathorst, Dictyophyllum nils- 

 soni is a fairly abundant species in the Rhaetic beds at Palsjo and Hor 

 in southern Sweden, and he has figured some magnificent examples 

 with as many as 18 pinnules or segments. The number of segments 

 appears to range from 6 to 9 on a side, or from 12 to 18 in the whole 

 frond. 



The Matanuska specimens, although known only from pieces of 

 small size, give evidence of having been as large as, or even larger, 

 than the maximum size showii in Nathorst's figures. Thus, the 

 fragments shown in plate 82, fig. 1, might well have come from the 

 middle of a segment similar to that shown in Nathorst's plate 2.^ The 

 nervation in the Alaskan specimens is preserved with great fidelity, 

 as may be noted from the figures. 



The Swedish specimens show such a range in size and outline that 

 Nathorst has been induced to give them a number of form or varietal 

 names, at least two of which are recognizable in the Alaskan material. 

 Thus, fig-ures 1-3 are referable to Nathorst's form genuinum, while 

 figure 4 seems to be form hrevilohatum.. 



Occurrence. — 6700. Upper Matanuska Valley, Alaska. Crest of 

 spur between first and second tributaries entering East Fork of 

 Boulder Creek above its mouth. Elevation, 4,780 feet. 



SAGENOPTERIS?, species. 



Plate 81, fig. 2. 



The collections from the Matanuska region include the fragment 

 here figured, which represents the apical portion of a small very obtuse 

 leaf. The fragment is about 4 cm. long and a httle less than 2 cm. 

 wide, and gives httle evidence of an increase in size toward the base. 

 The substance of the leaf is extremely thick and the nervation, with 

 the exception of the midrib, is made out with difficulty. The mid- 

 rib is very slender, but appears to reach quite to the apex. The 



1 Lindley and Hutton, Foss. flora Great Britain, vol. 2, 1834, pi. 104. 



2 In this connection it may be worth while to point out an error into which Seward has fallen in consid- 

 ering the type-species. In his Jurassic flora of the Yorkshire Coast, 1900, p. 123, he says: "In 1828, Brong- 

 niart proposed the name Phleboptcris philUpsi for the plant figured by Lindley and Hutton in 1834 as Dk- 

 tyophyllum rugosum; the latter name is quoted by the French author as a synonym, although the plant 

 was not described in the Fossil Flora until 1834. We must assume, therefore, that Brongniart saw the 

 description by the English authors some years before Lindley and Hutton published their work." As a 

 matter of fact Brongniart 's Hisloire, although bearing the title-page date of 1828, was actually published 

 in parts extending over the period from 1828 to 1838, and the parts 10 and 11, covering pages 337 to 416, and 

 plates 131 to 134, within which falls the description of Phlebopteris pUllipsi, was not issued until 1836, as 

 worked out by Zeiller in his Valenciennes flora, 1888, p. 702. This shows that Brongniart must have had 

 Lmdley and Button's work before him, and his Phlebopteris pMllipsi naturally and legitimately becomes a 

 synonym of Dictyophyllum rugosum. 



3 Kongl. Svenska Vetenskaps-Ak. Handl., vol. 41, 1906, pi. 2. 



