8 NATHORST. FOSSIL PLANTS OF FRANZ JOSEF LAND. [norw. pol. EXP. 



SPHENOPTERIS, Brongniart. 



Sphenopteris sp. a. 



PI. I. figs. 2 and (magnified) 44. 



It is possible that this small fragment belongs to a species not previously 

 described. It is, however, difficult to decide whether it should be brought under 

 Cladophlebis or Sphenopteris, though the latter seems more probable. The 

 pinnules certainly present an obvious midrib, but it is possible that these pin- 

 nules themselves, in a more developed stadium, are divided in the manner 

 characterising Sphenopteris, and that the specimen in question is only the 

 very apex of the secondary segment. Owing to the undulating margin of 

 the pinnules, there is a certain resemblance to Asplenium petruschinense 

 Heer, from the Jurassic strata of Siberia (Flora fossilis arctica, vol. 5), but 

 it is not possible to decide whether this resemblance points to any real affi- 

 nity. The same holds good concerning Asplenium Gsekanowskianum Heer, 

 from the Atyrkan, a tributary of the Lena River at Lat. 71° 15' between Lena 

 and Olenek. (Flora fossilis artica, vol. 5). 



The specimen is especially interesting because the epidermic cells have 

 made distinct impressions in the rock substance, so that their oval form can 

 be observed under a strong magnifying lens, or the microscope. 



Sphenopteris sp. b. 

 PI. I. figs. 3 and (magnified) 45. 



This fragment belongs to the Sphenopteris [Thyrsopteris) Murrayana- 

 type which is wide-spread in the Jurassic strata, but it is insufficient for any 

 definite determination. 



Sphenopteris sp. c. 



PI. I. figs. 4 and (magnified) 46. 



Of this type also there is but the fragment represented, which is too in- 

 complete for any certain determination. It may be compared with Sphenop- 

 teris (Thyrsopteris) MaaUana Heer from Siberian strata (Flora fossilis arc- 

 tica, vol. 4), but also shows some similarity to Sphenopteris denticulata 

 Brongn. from the Yorkshire oolite, as also to Bicksonia borealis Heer from 

 the strata of Northern Siberia. The venation is probably more intricate than 

 the drawing represents, but it is difficult to make it out. 



