[I'ENHAi.i.cw] NORTH AMKHICAN SI'1X'1E.< (>K DADoXYLoN 



(31 



1877, 257, 260; Goppert, Die Foss. Flor. der Perm. Form. 1864-18C5, 

 249-2.39 ; Goppert, Die Flor. der Sil. Dev. und unt. Kohlenform., 

 1859, 548-550; Goppert, Die verst. Walderi im nord. Iloheni. und 

 Schles., 1859, 7, Pis. 1. & II.; Goppert, Foss. Flor. des L'lxsrgangsg., 

 1851, 252-256; Williamson, Org. of the Foss., PI. of the Coal Meas., 

 Trans. R. Soc, 1872, IV., 377; Trans. R. Soc, 1876. VIII.. 222. Pis. & 

 Figs.; Goppert, Foss. Conif., ISoO, 230-236; Engler & Prantl. Gen. 

 Plant, II., 1, pp. 26, 116; Solms-Laubach, Foss. Bot, 1891, 104-122 & 

 80-84; Wlham, Int. Struct. Veg. Foss., 1833. 



Trausvvixe. — Pith of the Sternbergia type: the cells large, thin-walled, often 

 re-sinoiis. Growth rings when present obscure, rarely somewhat 

 conspicuous. Specialised resin cells and canals wholly wanting 

 except in the bark where they take the form of tubular, branching 

 canals without epithelium, extending in the general direction of the 

 stem axis. Tracheids in regular, radial rows, conspicuously squarish. 



Radkil. — Elements of the protoxylem spiral and scalariform, and often show- 

 ing a graduated transition into tracheids with bordered pits. 

 Tracheids with hexagonal, bordered pits throughout, on their radial 

 walls only, in 1-5 rows. Ray cells usually oi one kind only ; the 

 upper and lower walls thin and not pitted; the terminal walls thin, 

 not pitted, generally curved; the lateral walls with bordered pits. 



Tangent ial. — Medullary rays rather numerous, 1-seriate or often 2-seriate in 

 part. 



Synopsis of Species. 



The following sjoiopsis is given provisionally as an aid to identifica- 

 tion of the various species, without implying the absolute value of the 

 differential characters. 



I. — Groicth rings present. 



1. C. pennsylvanicum. 

 II. — (Jrotcth rings obscure or obsolete. 



A. Ray elements of two kinds, tracheids and parenchyma. 

 Bordered pits in 2-3, rarely four rows. 



Ray cells Itang.) oval or oblong, often narrow. 



2. C. Clarkii. 



B. Ray elements of one kind only. 

 Bordered pits in groups of 6-13. 



Pits on the lateral walls of the ray cells 3-6, chiefly 4 per tracheid. 



3. C. Nowbcrryi. 

 Bordered pits in one row. compressed. 



Ray cells (tang.) broad, round or squarish. 



4. C. recentium. 

 Bordered pits in 1-3, chiefly 2 rows. 



Ray cells ((ing.) broadly oval. 



Ray cells about 31-57 mic. broad. 



