xeviii proceedings of the geological society, [vol. lxxix, 



plant named by Nathorst TJmrsopliyton, and often confused with 

 JPsilophyton. Thursopliyton is the plant called by J. W. Salter 

 Lycopodites milleri, and by W. Carruthers Psilophyton decheni- 

 anum ; it is, as Kidston & Lang have stated, almost certainly 

 identical with Asteroxylon from Aberdeenshire. In Thursopliyton 

 the distinguishing feature is the jwssession of imbricate scale-like 

 leaves, in place of the spinous appendages of Psilophyton : it is 

 another of the earlier Lycopodiaceous genera. 



Several years ago some casts of longitudinally-ribbed stems were 

 described, from Lower Devonian rocks in the Shetland Islands, as 

 possible allies of the genus Catamites. The largest specimen that 

 I have seen is one in the Edinburgh Museum, 48 cm. long and 

 13 cm. in diameter. Similar ribbed stems have been found at both 

 Lower and Middle Devonian localities on the mainland of Scotland, 

 and they are often spoken of as the ' Corduroy Plant.' It is 

 possible that these casts may belong to plants similar to the large 

 Protolepidodendra from Naples and Grilboa : a regular ribbing 

 characterizes the lower parts of those stems, and on some specimens 

 of Cyclostigma from the Upper Devonian of Ireland and Bear 

 Island precisely similar ribs are not infrequent. 



There are many other plant-remains from Middle Devonian 

 floras, especially from Bohemia, which cannot be dealt with in a 

 general survey; but a comparison of the illustrations given by 

 Potonie & Bernard with specimens from the older Devonian rocks 

 of Scotland convinces me that there is a strong likeness between 

 the two floras. From Western Norway Nathorst has described 

 two new genera, Brbggeria and Hyenia ; the former, represented 

 by branched axes bearing relatively long terminal clusters of 

 sporangia, may be a forerunner of the Upper Devonian type illus- 

 trated by such a genus as Archceopteris. Hyenia, as Nathorst 

 suggests, would seem to be related to the Sphenophyllales. 



The older Devonian floras are, in the first place, characterized bv 

 the relative abundance of members of the Lycopod phylum : some 

 leafless and rootless like Hhynia and Hornea ; some, like Astero- 

 xylon and the impressions represented by Thursopliyton, with 

 crowded scale-like leaves ; others in which spine-like appendages — 

 as in Psilophyton and Arthrostigma — took the place of normal 

 leaves; and some arborescent forms having leaves and leaf-scars 

 more akin to those of the later Lepidodendra and a swollen rootlet- 



