454 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 51. 



To the best of present knowledge and belief, then, the Matanuska 

 localities are thought to be of the same age as the Bomhohn deposits, 

 and the question only remains : What is that age ? In the works of 

 MoUer, Nathorst, and others the Boniholm locahty is referred to as 

 Khaetic or Liassic, there apparently being the same difficulty there, 

 as in many other parts of Europe, in drawing the fine between the 

 Triassic and Jurassic. Taking everj^hing into accomit in the present 

 connection, such as the Jurassic affinity of certain of the forms, the 

 absence of known plant-bearing Triassic rocks in Alaska, the appar- 

 ently Lower Jurassic indication of the associated invertebrates, etc., 

 all give weight to the reference of these rocks to the higher of the 

 two alternatives. The material under consideration from the Mata- 

 nuska Valley is, therefore, regarded as of Lower Jurassic (Liassic) 

 age. This is the oldest, well-defined Jurassic flora known to the 

 writer in North America. 



It may be mentioned that the plant-bearing beds that are possibly 

 of Lower Jurassic age have been found at Cold Bay on the Alaska 

 Peninsula. The fossil plants obtained form these beds Got 3109) 

 are not well preserved and apparently include only two species which 

 have been provisionally identified as Glossozamitesi schrenTciil and 

 Pterophyllum ? species. These species probably are not identical with 

 any of the forms here described. 



ENUMERATION OF THE SPECIES. 



CLADOPHLEBIS HIRTA? Mttller. 



Plate 81, fig. 3. 



Cladophlebis hirta Moller, Bidrag till Bornholm fossila flora, Pteridophyter: 

 Kong. Fysiografiska Sallskapots, Handl., vol. 13, 1902, p. 30, pi. 2, figs. 23, 

 24; pi. 3, fig. 2. 



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

 spur between first and second tributaries entering East Fork of 

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



DICTYOPHYLLUM mLSSONI (Brongnjart) GOppert. 



Plate 82, figs. 1^. 



Dictyophyllum nilssoni (Brongniart) Goppert, Gattungen d. fossilen Pflanzen, 

 pts. 5 and 6, 1846, p. 119 [153]. — Nathorst, Bidrag till Sveriges fossila flora, 

 Kongl. Svenska Vetenskaps-Ak. Handl., vol. 14, No. 3, 1876, p. 25, pi. 1, 

 fig. 14; pi. 4, figs. 6-8; pi. 5, figs. 1-5; pi. 6, figs. 2-3; pi. 7, figs. 1, 2; Beitrag 

 e fossilen flora Schwedens, 1878, p. 14, plates and figures the same as in the 

 preceding paper; tjber Dictyophijllum u. Camptopteris spiralis: Kongl. 

 Svenska Vetenskaps-Ak. Handl., vol. 41, 1906, p. 5, pi. 2; pi. 3, figs. 2-8. 



Phlebopteris nilsonii Brongniart, Hist. v^g. foss., 1836, p. 376, pi. 132, fig. 2. 



So far as known to the writer this is the second time the presence 

 of Dictyophyllum has been noted in North America. The genus was 



