THE FLORA OF THK COAL FORMATION. 449 



9. Pecopteris, Brongn.— This genus is intermediate between the last 

 and Xeuropteris. The leaflets are attached by the whole base, but 

 not usually attached to each other; the midrib, though slender, attains 

 to the summit ; the ncrvures are given off less obliquely than in Neu- 

 ropteris. This genus includes a large number of our most common 

 fossil ferns. 



10. Beinertia, Goeppert. — A genus established by Goeppert for a 

 curious Pecopteris-like fern, with flexuous branching oblique nervures 

 becoming parallel to the edge of the frond. I have placed in it, with 

 some uncertainty, one of our species. 



11. llymenophyUitcs^ Goeppert. — These are ferns similar to Sphen- 

 opf.eris, but divided at the margin into one-nerved lobes, in the manner 

 of the modern genus Hymenophyllum. 



12. Palceopteris^ Geinitz. — This is a genus formed to include certain 

 trunks of tree ferns with oval transverse scars of leaves, 



1 3. Caiilopteris^ Lindley and Hutton, — is another genus of fossil 

 trunks of tree ferns, but with elongate scars of leaves. 



14. Psaronius, Cotta. — Includes other trunks of tree ferns with 

 alternate scars or thick scales, and ordinai'ily with many aerial roots 

 grouped round them, as in some modern tree ferns. 



15. Megaphyfon, Artis. — Includes trunks of tree ferns which bore 

 their fronds, which were of great size, in two rows, one on each side 

 of the stem. These were very peculiar trees, less like modern ferns 

 than any of the others (Fig. 167). My reasons for regarding them 

 as ferns are stated in the following extract from a recent paper : — 



" Their thick stems, marked with linear scars and having two rows of 

 large depressed areoles on the sides, suggest no affinities to any known 

 plants. They are usually ranked with Lepidodendron and Ulodendron, 

 but sometimes, and probably with greater reason, are regarded as allied 

 to tree ferns. At the Joggins a very fine species (M. magnificum) 

 has been found, and at Sydney a smaller species [M. humile) ; but 

 both arc rare and not well presei'ved. If the large scars bore cones 

 and the smaller bore leaves, then, as Brongniart remarks, the plant 

 would nnich resemble Lepldopldoios^ in which the cone-scars are thus 

 sometimes distichous. But the scars are not round and marked with 

 radiating scales as in Lepidophloios ; they are reniform or oval, and 

 resemble those of tree ferns, for which reason they may be rcgai-ded 

 as more probably leaf-scars ; and in that case the smaller linear scars 

 would indicate ramenta, or small aerial roots. Furtlier, the plant 

 described by Corda as Zippea disticha is evidently a Megap/iyton, and 

 the structure of that species is plainly that of a tree fern of somewhat 

 peculiar type. On these grounds I incline to the opinion of Geinitz, 



