452 



MR WM. T. GORDON 



necessary, and I have based my comparison on the author's description. It was de- 

 scribed from impressions, so that the specific characters depend on the leaf-bases. (Only 

 halonial branches can be compared, as my stems are all in that condition.) In L. 

 Scoticus there is a bending back of the leaf-bases round the halonial tubercules into a 

 rosette, and the leaf-bases themselves are smooth, rounded, elongated ; in L. Scottii, 

 no rosettes have been observed at the base of the cone stalks, and the leaf-bases are 

 smooth, keeled, elongated. Towards the scar the keel disappears, and from that point 

 to the scar the leaf-base is rounded, getting flatter and flatter as the scar is approached. 

 On the under surface of the leaf-base the ridge is more prominent than in L. Scoticus. 



Summary. 



Lepidophloios Scottii occurs in the Pettycur limestone in the Calciferous Sandstone 

 series of Fife. The species is named in honour of Dr D. H. Scott, F.R.S., and is founded 

 on sections 960 to 976 in the Scott collection and about 180 sections in the Gordon 

 collection. It is a true Lepidophloios, having all the characters of that genus. The 

 stem is typical of the Lepidodendrese, is in this case "halonial," and is clothed with 

 leaf- bases. The leaf-trace is collateral, the xylem mesarch, and a parichnos strand 

 occurs beneath the bundle. The cone branches have no pith, are typically halonial, and 

 are quincuncially arranged. The main stem has a pith with short tracheides and some- 

 times long tracheides scattered in it. The specific characters derived from the leaf-bases, 

 and irrespective of those derived from the structure of the stele, are as follows : — 



1. The leaf-base is keeled for three-quarters of its length, and then slopes suddenly 



down to the leaf-scar with an unkeeled, concave surface. 



2. The ligule canal is short, straight, and has its orifice covered by the overlying 



leaf-bases. 



3. There is a pallisade-like layer round the ligule pit. 



4. The parichnos only forks a short distance below the leaf-scar. 



O.C.3 



O.C.j 



; o.c, ; o.c. 3 = three layers of outer cortex ; o.c 2 is the 





secondary tissue (periderm). 



O.C.2 



m.c. = middle cortex. 



O.C.I 



i.e. = inner cortex. 



ph. = phloem (physiological). 





x. = xylem. 





p. = pith. 





l.t. = leaf-trace. 





1. b. = leal-base. 



m.c. 



b. — section of reticulum of cells with dark- 



i.e. 



brown contents. 



ph. 





X. 





p 





