THORE G. HALLE, CIOUGHTONIA, A PROBLEMATIC FOSSIL PLANT 3 
ency. The vegetable tissue forms a thin film on the impress- 
ions, and after the usual treatment the cuticles of the two sides 
can be examined microscopically. There is very little difference 
as regards the structure of the epidermis, between the two sides. 
On one side, probably the lower one, the course of the veins is 
faintly marked by rows of more elongated cells. Otherwise the 
tissue is very uniform and consists of square or irregularly poly- 
gonal cells. There are no stomata on either of the two sides 
(pl. 2, figs. 4 and 5). 
It is not possible to arrive at a definite conclusion as to the 
real nature of these fossils. Their general habit does not sug- 
gest fern-fronds. The broad, truncate base and the wrinkled 
surface are characters which are not common in ferns, but more 
important is the fact that the epidermis possesses no stomata. 
There is no reason to believe that the fronds belonged to sub- 
merged parts of aquatie plants, nor can they be compared with 
the filmy leaf-structures of the Hymenophyllacee, the strong 
development of the cuticles not being in accordance with such an 
interpretation. The absence of stomata may therefore be taken 
to indicate that the fossils do not represent ordinary green 
leaves, either of ferns or of spermophytes. More probably they 
are of the nature of either scale-fronds or some foliar organs of 
the floral region of a spermophyte. The shape and the thin tex- 
ture of the lamina appears to be more in favour of the latter view. 
The fronds may be imagined to have belonged to the inflores- 
cence of some highly developed gymnospermous plant, perhaps 
similar to Williamsonia. It is even possible that these »bracts » 
were coloured. At any rate, it is evident from the absence of 
stomata that they did not perform the functions of ordinary 
green leaves. Their outward resemblance to large petals such 
as occur in some of the lower groups of the angiosperms is, 
indeed, striking. This resemblance may be quite accidental 
and cannot, of course, be regarded as indicating any similarity in 
morphological nature; but it is evident that foliar organs which 
can be suspected to have belonged to the inflorescences of the 
highest gymnosperms are of very great interest. It is im- 
portant, therefore, that when dealing with fossils like the pre- 
sent specimens the possibility should be considered that they 
may belong to the floral region. 
There have been described from the Mesozoie rocks of other 
distriets some fossils which may be compared with the present 
