136 PROCEEDINGS OP TKE GEOLOGICAL SOCIETY. [DoC. 20, 



Sydney, on the contrary, Pecopteris abhreviata and Alethopteris ner- 

 vosa are the most common ferns. But though fronds of ferns are 

 comparatively rare at the Joggins, except in a few beds, and these 

 holding principally the species Alethopteris lonchitica, bundles of 

 scalariform vessels referable to ferns occur very plentifully in the 

 coarser parts of the coal-beds, and would seem to indicate that vast 

 quantities of stipes and fronds have been resolved into coal. It is 

 to be observed, however, that it is not in all cases possible to di- 

 stinguish the vascular bundles of ferns from those of the leaves of 

 Sigillarioid and Lycopodiaceous plants. (Fig. 67, PL XII.) 



Trunks of two species of tree ferns of the genus Palceopteris have 

 been found in Fova Scotia and New Brunswick, and also obscure 

 fragments, probably of Caulopteris and Psaronius. (Figs. 35 & 36, 

 PI. YIII.) 



8. Megaphyton. — These are perhaps the most curious and puzzling 

 plants of the coal. Their thick stems, marked by 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 Lepi- 

 dodendron 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 are rare and not well preserved. 

 If the large scars supported cones and the smaller leaves, then, as 

 Brongniart remarks, the plant would much resemble Lepidopliloios, 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 regarded as more probably leaf-scars* ; 

 and in that case the smaller linear scars would indicate ramenta, or 

 small aerial roots. Further, the plant described by Corda as Zippea 

 disticha is evidently a Megaphyton, 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, that these curious trees 

 were allied to ferns, and bore two rows of large fronds, the trunks 

 being covered with coarse hairs or small aerial roots. At one time 

 I was disposed to suspect that they may have crept along the ground ; 

 but a specimen from Sydney shows the leaf- stalks proceeding from 

 the stem at an angle so acute that the stem must, I think, have been 

 erect. Prom the appearance of the scars it is probable that only a 

 pair of fronds were borne at one time at the top of the stem ; and if 

 these were broad and spreading, it would be a very graceful plant. 

 To what extent plants of this type contributed to the accumulation 

 of coal I have no means of ascertaining, their tissues in the state 

 of coal not being distinguishable from those of ferns and Ljco- 

 podiacea?. 



. The species Megaphyton humile had, like Corda's Zippea disticha, 

 a thick central axis striated longitudinally, and giving off very thick 

 bundles of fibres, and probably scalariform vessels, to the bases of 

 the leaves. (Pigs. 33 & 34, PI. YIII.) 



* This is the Tiew of Lindley, * Fossil Flora,' p. 116. 



