105 
Tooth-leaf Fern. — Odontopteris. 
Pinnae pinnatifid. The leaflets are very thin, and adhere 
to the rachis of the pinnae by their whole base. Mid-rib 
of leaflet absent or rudimentary. Veins equal, simple, or 
forked, mostly springing side by side from the base of the 
leaflet passing onwards towards the point. ‘‘ In their gene- 
ral aspect, these plants resemble some South American 
species of Osmunda. Five species only are known, all of 
which belong to the most ancient coal strata.”* 
Four genera of Fossil Ferns have now been mentioned, 
that the nature of their classification may be understood. 
It is apparent that the form of the leaflets, and their attach- 
ment, and the distribution of their veins is the basis of the 
system. AVhoever examines the British Ferns cannot fail 
to notice that in the leaflets there is generally a mid-vein 
of nearly equal thickness throughout, and that from that 
mid-vein side-veins issue right and left, which are sometimes 
simple, sometimes forked. Exactly the same is the case 
with the Fossil Ferns. In the Moonwort, (BotrycJiivm 
Lunario) there is no mid-vein, but the veins radiate from 
the base. (See plate III.) To these correspond the Wedge- 
leaf Fossil Ferns (Sphenopterides.J 
With regard to fructification, it has been observed that 
in a large number of Fossil Ferns none has been discovered. 
In the Embroidered Ferns (Pecopterides) fronds having 
clusters of them are not uncommon. These clusters are on 
the back of the leaflets in rows on each side the mid-vein, 
in accordance with what occurs in the Shield Ferns (Las- 
treed.) A species also of the Wedge-leaf Fossil Ferns, 
(Sphenopteris Nephrocarpa) has been brought from the 
oolitic deposits of Scarborough, which has at the tip of the 
lobes of the leaves a kidney-form cover resembling the 
covers of the Male Fern (Filix mas) The Nerved-leaf 
Ferns, (Near opter ides) have lance-shaped clusters, and thus 
in some manner resemble the Spleenworts. In the Eoyal 
Flowering Fern, not only is the fruit at the summit of the 
frond, but often at the ends of the pinnae or branches, so 
* Mantell’a Medals of Creation, 
