1546 



PHANEROGAMS. 



Fig. 1410. — Leaf of Quercus 

 conferta. Recent. Reduced. 

 (After Schenk.) 



to elongated leaves (fig. 1409), from the Upper Cretaceous and 

 Eocene of both Europe and North America, which appear to be in 

 some respects intermediate between those of 

 Castanopsis and the earlier species of Oaks. 

 The leaves of Quercus (Oak) are subject to 

 an enormous amount of variation, rendering 

 the determination of fossil forms a work of 

 extraordinary difficulty. One of the most 

 ordinary and characteristic types of leaf is 

 shown in fig. 1410, but in the early Ter- 

 tiary and Upper Cretaceous we meet with 

 long slender oak4eaves approximating to 

 those of Castanea in general contour. The 

 earliest recorded occurrence of the genus 

 is in the Dakota stage, and it is abundant- 

 ly represented throughout the Tertiaries ; 

 leaves, from the Tertiary of Australia, in 

 which country oaks are now absent, have 

 been described as Quercus, but doubt has been thrown on this 

 determination. In the Juglandacece, the genus Juglans (Walnut) 

 probably dates from the Upper Cretaceous of America and Green- 

 land ; the Tertiary species of 

 which a leaf is figured in the 

 woodcut occurs on both sides 

 of the Atlantic, and appears to 

 be closely allied to the existing 

 J. regia. The name Jugland- 

 ites has been applied to leaves 

 from the Upper Cretaceous and 

 Eocene of Europe, which are 

 believed to indicate an allied 

 type. Carya (Hickory), now confined to America, is recorded from 

 the Cretaceous of that country, and occurs in both the European 

 and American Tertiaries. Similarly the Old World Pterocarya is 

 represented in the Tertiaries of both hemispheres, while the Oriental 

 genus Engelhardtia occurs in the Upper Eocene of Aix, where it 

 has been described as Palceocarya. In the Myricacece the single 

 genus Myrica makes its first appearance in the Upper Cretaceous 

 of Greenland and North America, and is common in the Tertiaries. 

 Of more palaeontological importance is the family Salicacece, in which 

 both Populus (Poplar) and Salix (Willow), (fig. 141 5, d), date from 

 the Upper Cretaceous. A leaf from beds at Komi in Greenland, 

 which have been regarded as Lower Cretaceous, has, indeed, been 

 described as Populus, but according to Mr J. S. Gardner on totally 

 insufficient grounds ; but Sir J. W. Dawson considers that Salix 



Fig. 141 1. — Leaf of Juglans acuminata ; from 

 the Miocene of Europe. Reduced. (After 

 Schenk.) 



