DESCRIPTIVE CATALOGUE 



leading types of the principal families. Similarly, in the rela- 

 tively few important papers dealing with fossil Dicotyledons, 

 essential details generally remain undescribed for instance, 

 neither Felix (1883) nor Schenk (1883) illustrates the thickening 

 or pitting of the medullary ray-cells iu the woods discussed. 



As a consequence, I have not attempted any exact determina- 

 tion of the still earlier Dicotyledons here described, but have en- 

 deavoured to illustrate adequately the details of their structure 

 by photographs and line-drawings. When similar illustrations 

 are available of the living plants, palaeontological determinations 

 may be attempted. 



The fact of prime importance, however, viz. that Dicotyledons 

 existed in this country in Aptian times, is demonstrated by 

 these specimens ; while it is also clear that they appear to 

 have been highly specialised types, and to show little evidence 

 of any " primitive " features. Though it has not been possible 

 to place them in any given family, one by one their details may 

 be matched in the woods of living forms. 



Hence, though these specimens have a peculiar interest, as 

 they are the earliest Dicotyledons of which the anatomy is 

 known, from any part of the world, they are not in any s. 

 " pro-angiospermic," and the really primitive iorms are still 

 awaited. 



Genus CANTIA, nov. 



As only one specimen of this type has as yet eome to light, 

 the diagnosis of the genus and species will be given together. 



Cantia arborescens, sp. nov. 

 [Plates XXV1-XXVI1I ; text-figs. 70-78.] 



Diagnosis. The species is founded on the decorticated second- 

 ary wood. A large woody trunk, forming timber 30 cm. and 

 more in diameter, with normal growth-rings. Wood consisting 

 of small quantities of fibre-tracheids and parenchyma, with 

 large numbers of isolated circular vessels uniformly distributed, 

 averaging 30-50 ju in diameter. Medullary rays numerous, all 

 uniseriate, all the ray-cells with thickened and pitted walls, 

 numerous circular or oval pits, sometimes bordered in the 

 radial walls. Vessels pitted variously, with round, oval, and 

 scalariform pits. Wood-fibres with large, round, bordered pits. 



