[PENHALLOw] NORTH AMERICAN SPECIES OF DADOX YLON 79 
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DESCRIPTION OF THE FIGURES. 
1.—Cordaites Brandlingii. Transverse section showing extent of devel- 
opment in the growth rings. S.W.—Summer wood. x 48. 
2.—Cordaites hamiltonense. Transverse section of the inner bark, 
showing (c) the cambium region, (pr.) the ordinary parenchyma 
and bast structure, (r.c.) the resin canals forming the outer 
limit. x 48. 
3.— . Transverse section of the middle bark 
in continuation of Fig. 2, showing (r.c.) resin canals, (pr.) ordin- 
ary parenchyma tissue. x 48. 
4 — 
sei .. Transverse section of the middle bark 
oe b) has fhe outer bark (o.b) which is in process of decom- 
position. x 48. 
5.—.. . .. .. .. Radial longitudinal section of the inner 
bank showine (m.r.) medullary rays at their entrance from the 
wood, (c.) the cambium region and (pr.) the ordinary structure 
of the parenchyma. x 48. 
6.—.. . .. .. .. Radial longitudinal section of the inner 
and. middie balk in continuation of Fig. 5, showing (r.c.) the 
resin canals and (pr.) ordinary parenchyma structure. x 48. 
ste . Radial longitudinal section of the outer 
dde. park! showing (pr.) ordinary parenchyma structure and 
(r.c.) resin canals. x 48. 
8.—Cordaites Clarkii. Transverse section of the stem showing (r.c) 
resin cells in the pith, vascular elements of the protoxylem (v.), 
and the ordinary tracheids (tr.) x 48. 
9.—Cordaites Brandlingii. Radial section showing the structural details 
in the vascular elements of the protoxylem. x 180. 
=. 
10.—.. J. s4 2. 2. Radial “section in’ continuation of His) 9; 
shows passage of spiral into scalariform structure. x 180. 
11.—.. .. .. .. .. Radial section in continuation of Fig. 10, 
slewing transformation of scalariform structure into bordered 
pits of transversely elongated form, and finally into pits of the 
hexagonal type. x 180. 
12.—Cordaites Newberryi. Radial section showing disposition of the 
bordered pits. x 180. 
13.—Cordaites materiarium. Tangential section showing the general 
character of the medullary rays of the uniseriate type. x 48. 
14.—... . .. .. .. Tangential section from the same speci- 
men + showin the rays noe seriate in part. x 48. 
15.—Cordaites ohioense. Tangential section, showing the character of 
the medullary rays. x 48. 
16.—Cordaites Clarkii. Tangential section, showing the nature of the 
rays with parenchyma cells and tracheids, which latter appear 
chiefly in the contracted portions. x 61. 
17.—Cordaites materiarium. Radial section showing typical character 
of the bordered pits in two rows. x 180. 
18.—Cordaites acadianum. Radial section showing typical character of 
the bordered pits in 2-4 rows. x 180. 
