Seward: The Jurassic Flora of Yorkshire. 5 
named ; it denotes ferns characterised by entire or slightly 
-obed leaflets like those of many recent species, such as the Male 
fern and other British types. It is highly probable, however, 
that the very widely-spread species Cladophlebis denticulata 
(fig. 1) characterised by its falcate and often finely denticulate 
pinnules, is a member of the Osmundaceae, a family still 
represented in Britain by the royal fern Osmuda regalis. The 
evidence for the correctness of this opinion is perhaps not 
sufficiently strong to justify the employment of a generic title 
which would definitely denote inclusion in the Osmundaceae. 
The great need in regard to fossil ferns is the discovery of 
specimens of fertile fronds, which would enable us to dertermine 
the nature of the sporangia, or of petrified examples throwing 
light on the anatomical characters of stems and leaves. 
The common Jurassic species Taeniopteris vittata Brongn, 
closely resembles, in the form of the leaf, the familiar Hart’s 
tongue fern, but hitherto no fertile specimens have been found, 
and we are in the dark as to the family position of this type. 
Recent work on the fern-like plants from Paleozoic rocks has 
shewn that the fern-type of frond is in itself a very uncertain 
guide as to systematic position; many of the supposed fern fronds 
from the Coal Measures are now known to have been borne 
by seed-producing plants distinguished by important features 
from true ferns. We are not justified in assuming that such 
leaves as those of Taeniopteris bore sori and sporangia identical 
with the spore-forming organs of recent genera; they may be 
leaves of cycadean plants, or even of species belonging to the 
extinct group of Pteridosperms. Specimens of another plant, 
Nilssonia tenuinervis Nath., or, as it has recently been re- 
christened by Nathorst, Nilssoniopteris tenuinervis, are fre- 
quently found in the Yorkshire plant-beds ; the leaves of this 
Cycad are almost identical with those of Taeniopteris, from 
which they differ in the absence or rare occurrence of forking 
veins, and in the continuation of the leaf lamina over the mid. 
rib. Sphenopteris.—The employment of this name also implies 
lack of information in regard to the relationship of the fronds 
so named to recent ferns, and it should remind us that more 
material is needed before we can regard species charac- 
terised by the lobed Sphenopteris leaflets as plants possessing 
any real botanical value. 
II].—FERNS WHICH IT IS POSSIBLE TO REFER TO A FAMILY- 
POSITION. [Laccopteris polypodioides Brongn. and Matonidium 
Goepperti Ett.|. The two genera Laccopteris and Matonidium are 
generally recognised as closely related to the Matonineae, a recent 
family of ferns now represented by two species in the Malay 
Archipelago. The comparison of fertile pinnae of Matonidium 
Goepperti (fig. 2), such as may be obtained from Hayburn 
igit Jan. I. 
