408 EXPLANATION OF PLATES I. AND II. 



No. 4. 



Plate II. is a representation of a segment of an impres- 

 sion of the upper surface of a palmately veined leaf, mag- 

 nified to rather more than twice its linear dimensions. 

 Though it bears a general resemblance in its nervation, 

 and in the areolae formed by the minor reticulating veins, 

 to a leaf of the Maple, it differs at least as a species from 

 the American maples with which it has been compared. 

 Many small circular depressions of different sizes are irre- 

 gularly distributed over the surface of the leaf; the more 

 perfect of them are pitted by twenty or more minute 

 points visible by the aid of a lens ; and in some the central 

 point is larger than the others, producing the .appear? 

 ance of an umbo, as in the dots of the Taxites figured 

 in Plate I. These depressions were of course produced by 

 bodies rising above the surface of the leaf and rough with 

 little points; their unequal dispersion on the leaf, much 

 of whose surface was smooth, is against their having been 

 produced by hairy glands, and they were most probably 

 moulded on fungi growing on the leaf. There are also 

 some smaller and deeper depressions, most frequent towards 

 the upper part of the leaf, but considerably less numerous 

 than the larger shallow ones. Two other fragments of im- 

 pressions, seemingly of the same kind of leaf, have footstalks 

 not complete, but exceeding an inch in length. One of 

 these, representing the upper surface of the leaf, has a few 

 circular depressions of both kinds ; on the other, which is 

 an impression of the under surface of the leaf, there are no 

 depressions. 



None of the impressions are so complete as to give 

 the whole outline of the leaf. The base runs at right 

 angles with the footstalk, and is entire for nearly an inch, 

 beyond which it is rounded off and crenated by almost 

 semicircular, minutely apiculated teeth, separated from one 

 another by very acute sinuses. The leaf appears at first 



