452 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



of the Lower Jurassic tuffs ' of Seldovia. They were largely, if not wholly, deposited 

 in marine waters, although the plants herein described are possibly indicative of 

 temporary terrestrial conditions. The plants have been found only in one small area, 

 but the marine invertebrates are widely distributed. The plants and the marine 

 shells have not been found in the same bed, nor have their precise relations been 

 determined. 



Neither the basal contact of these beds nor the rocks which underlie them have 

 been observed, these being the oldest rocks known in this district. They are over- 

 lain by Middle Jurassic beds which have yielded numerous fossils (8567), including 

 Sagenopteris goppertiana Zigno, together with a great variety of marine invertebrates. 

 The fauna of these overlying Middle Jurassic rocks corresponds closely to that of the 

 Tuxedni sandstone ^ of Cook Inlet, in which Sagenopteris goppertiana and other plants 

 have also been found. 



Tho plant material from the Matanuska Valley proves to be of 

 exceptional interest and, as so frequently happens in reconnaissance 

 work, it is perhaps of necessity unfortmiately Umited in amount. 

 The matrix containing the plants had a tendency to break up into 

 small pieces, with the result that there is hardly an entire leaf or 

 frond in the whole collection. In some cases the nervation is much 

 obscured, while in others, as for instance in the fragments of Didyo- 

 phyllum leaves, it is retained with remarkable fidehty. 



The stratigraphy and invertebrate paleontology, as set forth in 

 the preceding paragraphs by Doctor Martin, pomt to the reference 

 of these rocks to the Lower Jurassic, and it naturally becomes of 

 interest to ascertain the bearing of tho plants on this point. Follow- 

 ing is an enumeration of the species recognized from the combined 

 localities, the local distribution of each species being indicated 

 under the locahty number below: 



Cladophlebis hirta ? Holler 



Dictyophyllum nilssoni (Brongniart) Goppert. 



Sagenopteris ?, species 



Otozamites pterophylloidcs Brongniart MSS 



Otozamites bornholmiensis ? Moller 



Pterophyllum rajmahalense Morris 



Pterophyllum aequale (Brongniart) Nathorst.. 



Ctenophyllum angustifolium ? Fontaine 



Nilssonia polymorpha Schenk 



Pagiophyllum falcaturn Bartolin 



As all these forms, with the exception of the unnamed Sagenopteris, 

 are species previously known, they may furnish adequate information 

 as to their age values. In the fu^t place it may be pointed out 

 that, although geographically related only one of the 10 forms enum- 

 erated above — ^namely, Pterophyllum rajmahalense, which has been 



1 Stanton, T. W., and Martin, G. C, Mesozoic section on Cook Inlet and Alaska Peninsula, Geol. See. 

 America Bull., vol. 16, 1905, pp. 396-397. 



2 Martin, G. C, and Katz, F. J., A geologic reconnaissance of the Iliamna region, Alaska, U. S. GeoL 

 Survey Bull. 485, 1912, pp. 59-64. 



