ti-ENUAi.i.ou] .NORTH AMKJilCAN Sl'KClKS OF DADoX VL( )N 79 



DES(,'RIPTI0N3 OP^ THE FIGURES. 



Fig. 1.— Cordaitfcs Brandlingll. Transverse section showing extent of devel- 

 opment in the growth rings. S.W.=Summer wood, x 48. 



Fig. 2.— Cordaites hamiitoneuse. Transverse section of the inner bark, 

 showing (c) the cambium region, (pr.) ti^e ordinary parenchyma 

 and bast structure, (r.c.) the resin canais forming the outer 

 limit. X 48. 



^'^- ^■~ Transverse section of the middle bark 



in continuation of Fig. 2, showing (r.c.) resin canals, (pr.) ordin- 

 ary parenchyma tissue, x 48. 



^^" ■*"" Transverse section of the middle bark 



(m.b.) and the outer bark (o.b.) which is in process of decom- 

 position, X 48. 



^^^' ^~ Radial longitudinal section of the inner 



bark showing (m.r.) medullary rays at their entrance from the 

 wood, (c.) the cambium region and (pr.) the ordinary structure 

 of the parenchyma, x 48. 



'^' ^~ Radial longitudinal section of the inner 



and middle bark in continuation of Fig. 5. showing (r.c.) the 

 ^ resin canals and (pr.) ordinary parenchyma structure, x 48. 



^" '~ Radial longitudinal section of the outer 



middle bark, showing (pr.) ordinary parenchyma structure and 

 (r.c.) resin canals, x 48. 

 Fig. 8.-Cordaites Clarkii. Transverse section of the stem showing (re) 

 resin cells in the pith, vascular elements of the protoxylem (v.) 

 and the ordinary tracheids (tr.) x 48 

 Fig. 9.-Cordaites Brandlingii. Radial section showing the structural details 

 in the vascular elements of the protoxylem. x ISO. 



'^" '~ Radial section m continuation of Fig 9 



Fi 11 _ ^''"'^'"^ passage of spiral into scalariform structure, x 180. 



^ Radial section in continuation of Fig 10 



showing transformation of scalariform structure into bordered 

 pits of transversly elongated form, and finally into pits of the 

 hexagonal type, x 180. 

 Fig. 12.-Cordaites Newberryi. Radial section showing disposition of the 



bordered pits, x 180. 

 Fig. 13.-Cordaites materiarium. Tangential section showing the general 



Fi 14- ^^'■^''*^'" °^ ^^^ '"^'^""^^y '•ays of the uniseriate type. X 48. 

 '^ Tangential section from the same speci- 

 men showing the rays 2-seriate in part, x 48 



Fig. 15.-Cordaites ohioense. Tangential section showing the character of 

 the medullary rays. ;. 48. 



Fig. 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 



Fig. 17.-Cordaites materiarium. Radial section showing typical character 

 of the bordered pits in two rows, x 180 



Fig. 18.-Cordaites acadianum. Radial section showing typical character of 

 the bordered pits in 2-4 rows, x 180 



