The Internal Anatomy of ‘Nilssonia orientalis’. 
BY 
MARIE C. STOPES, D.Sc., Ph.D., F.L.S. 
Lecturer in Palaeobotany at Manchester University. 
With Plate XXVI and a Figure in the Text. 
AMONG the desiderata of Botany is information regarding the anatomy 
of the numerous plants in the Mesozoic rocks which are known only 
from impressions. The uncertain value of external impressions for phylo¬ 
genetic and systematic work has often been emphasized in recent years. 
Even among the Palaeozoic plants, so many of which are known by 
their internal anatomy, it is a rare and fortunate chance, or series of chances, 
which gives both internal anatomy and external impression of the same 
specimen. Such a fortunate chance has materialized in a nodule of 
Cretaceous age in the case of the plant hitherto known only as a leaf impres¬ 
sion by the name Nilssonia orientalis , Heer. 
Foliage impressions of this species have been described several times 
from Mesozoic rocks from the Orient. Nathorst 1 figures impressions of the 
plant in his ‘Beitrage zur Mesozoischen Flora Japans’, Yabe 2 figures 
fragments from Korea, and Yokoyama 3 records the same species for Japan. 
So that we know that the species was well distributed in the Orient in the 
Mesozoic times. 
Among my specimens of Cretaceous, plant-containing nodules from 
Japan was one which revealed, when the matrix was broken, a fragment 
of a fairly sharp external impression of foliage. The stone split so as to 
expose part of the leaf in surface view, and to retain the bulk of it embedded 
in its matrix. The exposed portion (see Fig. i, PI. XXVI) was enough to 
identify the leaf as that known as Nilssonia orientalis , Heer, and it was 
found possible to cut a series of sections through the remainder of the leaf. 
These sections, though not so perfect as could have been desired, yet show 
anatomical petrifactions of the tissues, from which it is possible to reconstruct 
1 Nathorst, A. G.: Beitrage z. Mesozoischen Flora Japans. Kais. Akad. d. Wiss. Wien, 1890, 
pp. 2-20, PI. I-VI. 
2 Yabe, H. : Mesozoic Plants from Korea. Joum. Coll. Sci. Tokio, xx, 1905, pp. 1-59, PI. I-IV. 
3 Yokoyama, M.: Jurassic Plants from Kaga, Hida, and Echizen. Jonrn. Coll. Sci. Tokio, 
iii, 1889. 
[Annals of Botany, Vol. XXIV. No. XCIV. April, igio.] 
