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FOSSIL FERNS. CLATHROPTERIS. 12h 
mid-rib strong; secondary veins anastomosing by arches, 
with large angular spaces, often unequally disposed; the 
finer veins are simple or divided ; the apex sometimes free. 
The fructification is punctiform, and placed at the apices 
of the veins. 
The foliage of these remarkable ferns has been mistaken 
for the leaves of dicotyledonous plants ; but M. Brongniart 
has demonstrated that they belong to the present family. 
Six species have been found in the Oolite and Lias. 
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Lien. 30. CLATHROPTERIS MENISCOIDES. 
Portion of a leaflet: the original 13 ft. long. 
Wealden? Scania. 
CLATHROPTERIS (latticed-leaf). Lign. 30.—Leaf deeply 
pinnatifid ; leaflets elongated, traversed by a strong midrib 
extending to the apex ; secondary veins numerous, simple, 
parallel, almost perpendicular to the midrib, united by 
transverse branches, which, with the finer veins, produce 
on the surface of the leaf a net-work of quadrangular 
meshes. 
This genus was instituted by M. Brongniart, for the re- 
ception of some very large fern-leaves from the shale. of 
Hoer, in Scania, which resemble in structure the foliage of 
the recent Polypodiwm quercifolium, a native of the East 
