No. 7.] DAWSON — SCOTTISH DEVONIAN PLANTS. 381 



I was under the necessity of giving them a special generic name, 

 nor could I with certainty affirm their specific identity with any 

 European species. The comparison of the Scottish specimens 

 with woody rootlets, though incorrect, is in one respect creditable 

 to the acumen of Salter, as in almost any state of preservation 

 an experienced eye can readily perceive that branchlets of 

 Psilophyton must have been woody rather than herbaceous, and 

 their appearance is quite different from that of any true Algae. 



The type of Psilophyton is my P. princeps, of which the 

 whole of the parts and structures are well known, the entire 

 plant being furnished in abundance and in situ in the rich 

 plant-beds of Gaspe. A second species, P. robust ius, has also 

 afforded well characterized fructification. P. elegans, whose 

 fruit appears as "oval scales," no doubt bore sac-like spore-cases 

 resembling those of the other species,. but in a different position, 

 and perfectly flattened in the specimens procured. The only 

 other Canadian species, P. glabrum, being somewhat different in 

 appearance from the others, and not having afforded any fructi- 

 fication, must be regarded as uncertain. 



The generic characters of the three first species may be stated 

 as follows : — 



Stems dichotomous, with rudimentary subulate leaves, some- 

 times obsolete in terminal branchlets and fertile branches ; and 

 in decorticated specimens represented only 'by punctiform scars. 

 Young branches circinate. Rhizomata cylindrical, with circular 

 root-areoles. Internal structure of stem, an axis of scalariform 

 vessels enclosed in a sheath of imperfect woody tissue and covered 

 with a cellular bark more dense externally. Fruit, naked sac- 

 like spore-cases, in pairs or clusters, terminal or lateral. 



The Scottish specimens conform to these characters in so far 

 as they are known, but not having as yet afforded fruit or inter- 

 nal structure, they cannot be specifically determined with cer- 

 tainty. More complete specimens should be carefully searched 

 for, and will no doubt be found. 



In Belgium, M. Crepin has described a new species from the 

 Upper Devonian of Condroz under the name P. Condrusianum, 

 [1875]. It wants however some of the more important charac- 

 ters of the genus, and differs in having a pinnate ramification 

 giving it the aspect of a fern. In a later paper [1876] the^. 

 author considers this species distinct from Psilophyton, and 

 proposes for it a new generic name Rhacophyton. In a note he 



