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TUE GEOLOGICAL HISTORY OF PLANTS. 



than horbnronus, and their appearance is qxiito different from that 

 of any true Alfitv. 



TIjo type of I'silnpfii/fon is my P. princepn, of wliich the whole 

 of the parts and structures arc well i<iiown, the entire plant being 

 furnished in abundance and in m'tu in the ridi |»lant-beds of Gaspc. 

 A second species, J'. rn/)Ufiliii.i, has also afforded well-characterised 

 fructification. P. eleyanfi, vfhosa fruit appears as "oval scales," no 

 doubt bore sac-like spore-cases resembling those of the other species, 

 but in a dilTercnt position, and perfectly flattened in the specimens 

 procured. The only other Caruidiati species, /*. glabrum, being some- 

 what different in appearance from the others, and not having af- 

 forced any fructification, must be regarded as uncertain. 



The generic characters of the first three species may be stated as 

 follows : 



Stems dichotomous, with rudimentary subulate leaves, sometimes 

 obsolete in terminal branchlets and fertile branches ; and in decor- 

 ticated specimens represented only by punctiform scars. Young 

 branches circinate. Rlnzomata 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 fniit or internal 

 structure, they cannot be specifically determined with certainty. 

 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 characters of 

 the genus, and differs in having a pinnate ramification, giving it ^\\q 

 aspect of a fern. In a later paper (1876) the author considers tn.s 

 species distinct from Psilophyton, and proposes for it a new generic 

 name Rhacophyton. 



The characters given by Mr. Carruthers, in his paper of 1873, for 

 the species P. Dechenianum, are very few and general : " Lower 

 branches short and frequently branching, giving the plant an oblong 

 circumscription." Yet even these characters do not apply, so far a? 

 known, to Miller's fucoids or Salter's rootlets or Goeppert's Ilalise- 

 rites. They merely express the peculiar mode of branching already 

 referred to in Salter's Lepidodetidron nothum. The identification of 

 the former plants with the Lepidodendron and Lycopodif.es, indeed, 



