74 DESCRIPTIVE CATALOGUE 



radiating towards the underside of the leaf (see text-fig. 16, ^>.7., 

 & PI. II, fig. 3), where the large size of these cells is apparent. 



The resin-canal is large and round, and is lined by a double 

 layer of smallish flattened cells. It appears to die out towards 

 the base of the leaf (see PI. II, fig. 3). 



A sclerised hypodenn, partly one layer and partly two layers 

 thick (see sc., text-fig. 16), runs all round the outer (under) 

 surface of the leaf. So far as I can judge from tho few sections 

 available, this is not interrupted by stomates, so it appears as 

 though the stomates must have occurred only in the grooves 

 between the leaves. 



The epidermis consists of flattened cells, about equal to t\v<> 

 hypodermic elements (see e., text- Jig. 1G). They appear to have 

 had an enormously thick cuticle (sec c., text-fig. 16). This 

 cuticle is very sharply petrified in several leaves, and there is no 

 doubt about its present extreme thickness, bu< it is very possible 

 that it may have swollen considerably during or before petri- 

 faction. It must, however, have been originally very thick to 

 have swollen so much. Outside it arc a number of well- 

 petrified mycelia of fungi. 



AFFINITIES. After the examination of many leaves of living 

 conifers, one recognises that the likeness of this fossil to Xeyuoia 

 (jiijantca is very noticeable. Without entering into any com- 

 parison with the other forms, it may be stated that I feel 

 no doubt at all that the fossil is a species of the living genus 

 Sequoia or an extinct genus extremely close to it. In their 

 main features the leaves of the fossil and of ^Kjuoia yujantea 

 are similar: both have small adpressed foliage with free 

 tips, both have a one- or two-layered hypodermic sclcren- 

 chyma, both have a single, large, central resin-canal with a flat 

 double-layered lining, both have a single vascular bundle with 

 two large masses of transfusion-tissue quite similar in structure 

 in each. As pointed out by Masters (Ib91, p. 251), the 

 position and number of the resin-canals in the leaf are very 

 constant features, and are consequently of diagnostic value, and 

 the single central resin-canal is found in the genus Sequoia at 

 the present day. 



Where the fossil differs from the living leaf, the differences 

 are relatively trifling and are only of specific value. The chief 

 differences are as follows : In the living Sc^u>/ia yiyantea 



