366 SCIADOPITINEAE [CH. 



Schenk states that these Ohgocene leaves are Dicotyledonous and 

 not the leaves of a Conifer. 



Specimens of fossil wood have been described exhibiting certain 

 features, especially the pitting of the medullary-ray cells, similar to 

 those' of Sciadopitys^ but the occurrence of such features in other 

 recent genera precludes a definite reference to any one type. 



SCIADOPITYTES. Goeppert. 



This name has recently been revived by Halle^ for two species of 

 Cretaceous leaves from Greenland, one of which, Pinus Crameri 

 Heer, though compared by Schenk with the leaves of Sciadofitys, 

 was not actually included in Sciadofitytes , while the other is a new 

 species, Sciadofitytes Nathorsti. Halle describes these leaves as 

 ' Conifer-like in habit, with a dorsal groove which is protected by 

 elongated papillae and whose epidermal tissue differs from that of 

 the rest of the leaf through a non-seriate arrangement of the cells 

 and the occurrence of stomata.' 



The outstanding feature of the leaves of Sciadofitys is the 

 double nature of the lamina and the morphological peculiarities 

 which have led to its recognition as a phylloclade; but, as Halle 

 admits, there is no evidence that the fossils are other than ordinary 

 simple leaves. The interesting characters described by Halle amply 

 justify "the use of a generic name separating the leaves from those 

 known only as impressions, without any structural features pre- 

 served, and referred to Pityofhyllum. It is, however, open to ques- 

 tion whether the name Sciadofitytes does not imply more than the 

 facts support. The leaves named by Heer^ Pinus Crameri are 

 about 12 mm. long and 2-5 mm. broad: the apex is bluntly rounded 

 and the base is shghtly widened. Halle points out that there is 

 evidence that the leaves were cyhndrical. The carbonised leaves 

 of this species form thick masses in the shale and excellent pre- 

 parations of the cuticle can be obtained. Halle considerably 

 extends Schenk's account of the epidermal characters. The 

 apparent midrib is a groove and there is no indication of a true 

 median vein. Rather large stomata are crowded in the groove and 



1 See page 138. 



2 HaUe(1.5)p. 508. 



3 Heer (68) i. PI. XLiv. figs. 7—18; (75) ii. PI. xxm. pp. 9—15; HaUe (15) 

 p. 509, PI. xni. figs. 1—13. 



