78 T. D. A. Cooker ell — Descriptions of Tertiary Plants. 



Sorbus nupta sp. nov., fig. 2. 



Leaf-blade about 6T mm long, and nearly as broad, with short 

 triangular lobes, the margin also sharply dentate. Structure 

 and appearance of leaf exceedingly like that of the Italian 

 S. cratcegifolia (Targ.-Tozz.) Wenzig, except that the Italian 

 plant has the base of the leaf strongly cordate, whereas in 

 the fossil it is strongly thoogh narrowly decurrent on the 

 petiole, extending for a distance of at least 10 mm . The strong 

 lateral veins are five or six pairs, as in S. cratcegifolia. The 

 sharp teeth are perhaps a little more in the manner of 8. lati- 

 folia Syme (rotundifolia Auctt.). There is a strong resem- 

 blance to S. intermedia in the lobing and toothing, but the 

 shape of the leaf is different. 



Florissant, in the Miocene shales, Station 13 B (1908). 



S. diversifolia is thus considered to be S. megaphylla X 

 nupta. The only objection to this parentage appears to lie in 

 the fact that diversifolia leaves are normally narrower than 

 those of hybrida, whereas from the breadth of S. nupta one 

 would expect them to be broader. 



There is reason to believe that the decurrent base of the 

 leaf is a primitive character ; the earliest form of leaf in the 

 Pyrus group may perhaps have been narrow-lanceolate, like 

 the living P. salicifolia Pall, from the Caucasus, which I had 

 an opportunity of examining in the Cambridge Botanical 

 Garden. From this, P. amygdaliformis Yill. (S. Europe) 

 affords a transition to the more ordinary types. The extreme 

 limit of modification is seen in Sorbus aucuparia var. laciniata 

 {Pyrus aucuparia var. laciniata Hort. Kew.), in which the 

 leaflets themselves are deeply lobed. 



