12 ERNST ANTEVS, THE SWEDISH SPECIES OF PTILOZAMITES NATH. 
Ptilozamites Heeri Narr. 
P2, gr P3, hgst 3 
Pterophyllum acuminatum (non auct.), NATHorRsT 1876 a, p. 33. 
Ptilozamites Heeri, NATHORST 1878, p. 11. 
> triangularis, NATHORST 1878, p. 11. 
> linearis, NATHORST 1878, p. 11. 
> Heeri, NATHORST 1878 a, pp. 7, 24; pl." 3, fig. 9. 
> NaATHORST 1879, p: 603; pl. 12, fgsiajöla=rervv. 
> triangularis, NATHORST 1879, p. 62; pl. 12, figs. 2, 3. 
» linearis, NATHORST 1879, p. 63; pl. 13, fig. 3. 
» acuminatus, NATHORST, 1879, p. 62; pl. 12, figs. 4?, 5. 
> acutangulus, NATHORST, 1879, p. 63; pl. 18, fig. 22?. 
3 Heeri, NATHORST 1880, p. 66. 
» > NÄATHOEST 18806, Dp. 1225 Pl. 2, Hösrös 
> » forma latior, NATHoORST 1886, p. 122; pl. 12, figs. 2, 3. 
»> >» forma angustior, NATHoRST 1886, p. 122; pl. 13, fig. 3. 
» acuminatus, NATHORST 1886, p. 122. 
> Heeri, SEWARD 1910, p. 546; fig. 361. 
SD 
Frond pinnate, very long and narrow, linear. Size very varying. HRachis very 
broad, undivided; its lower part bare. Pinnae close, but not imbricate, to some- 
what distant, short and broad; generally rhombic, but at other times almost trian- 
gular; apex blunt or rounded. Lowest pinnae very short and broad, rounded, often 
crescent-shaped. Venation more or less distinct, or at times quite invisible, consisting 
of a number of parallel or slightly radiating, forked veins. Consistence thick and firm. 
I have examined the cuticle in several specimens. ' There is no difference in 
its structure above the veins. The cells are irregular or almost isodiametrical. The 
upper cuticle is either considerably thicker than the lower one, or the difference in 
thickness between them is insignificant. In the former case the upper epidermis 
lacks, in the latter case possesses stomata, which are, however, rare. On the lower 
side the stomata are also rather few in number. They are equally distributed over 
the whole lamina. 
Pt. Heeri is represented by several beautiful specimens, some of which are 
preserved in such a state that it has been possible to detach them from the rock 
(pl. 3, figs. 2, 12). The largest complete frond reaches a length of 53 cm. and a 
breadth of 2-1 cm. (NATtHorsTt 1878, pl. 2, fig: 1). Adjacent pinnae do not quite 
agree in shape and size. Above all, they vary in breadth. As a rule, the segments 
are rhomboidal, but at times they are almost triangular. The distal margin is 
straight, and runs out into a blunt or rounded apex. The proximal margin is gene- 
rally at first parallel with the distal one, then bent in an all but right angle, or 
rounded from the very base: 
The fronds here referred to Pt. Heeri were originally described by NATHORST as 
different species, and here exactly the same fact presents itself as in the case of Ptilo- 
zamites Nilssoni. According as the collection has become more complete, it has 
proved that various limits were drawn too narrow and that in some cases what 
were considered different forms were identical. 
