16 ERNST ANTEVS, THE SWEDISH SPECIES ÖF PTILOZAMITES NATH. 
fig. 1) are rhomboidal: The veins are, as a rule, very distinct, dense, repeatedly 
bifurcating and generally radiating but at times almost parallel (pl. 1, fig. 10). 
NATHORST (1876 a, p. 35 and 1879, p. 64) remarks that ScHENK's statement that 
the veins are parallel cannot be correct; but there seems to be no reason why it 
should not be so. 
All the specimens from Scania are very fragmentary, but several are so typical 
that there can be no doubt as to their identity with BRAUNS's Nilssonia Blasii. 
NATHORST originally described the very insignificant fragments which were at 
his disposal under different names. In the critical addendum to his works on the 
fossil flora at Bjuf (1886, p. 123) he later on made the necessary alterations. At 
the same time he also pointed out the possibility of the fragment described as Ptilo- 
zamites sp. p. 60, pl. 15, fig. 16, NATHORST 1879; belonging to the present species. 
It is, however, probably better to regard the specimen in question as indeterminable. 
As for other fragments, ScHENK (1867, p. 170) united that which Brauns (1862, 
pl. 13, fig. 6) had described as Odontopteris laevis with Pt. Blasii; but it is, I think, 
doubtful if it belongs to this species. 
Though Pt. Blasu presents a striking resemblance to some Anomozamites-species, 
it is still more closely related to Ptilozamites, in which genus it certainly has its 
proper place. 
Owing to the considerable size of the segments, Pt. Blasii is well distinguished 
from other species of the same genus. The analogy with Pt. Heeri, however, is 
rather striking, and further the species presents a considerable resemblance to Ptilo- 
zamites Zuberi (SzAJN.) NATH. 
ZEILLER (1903, p. 535) compares his Ctenopteris Sarrani to Pt. Blasir, with which 
it shares the considerable size, the venation as well as, on a large scale, the shape 
of the pinnae. Ctenopteris Sarrani, however, is bipinnate, whereas Pt. Blasii is 
pinnate. But ZEILLER considers it not impossible that the two species agree also 
in this respect, for a specimen figured by BRAUNS (1862, pl. 14, fig. I a = SocHENK 
1867, pl. 40, fig. 1) is somewhat asymmetrical, and this fact, he thinks, indicates that 
the specimen in question may have constituted a pinna of a bipinnate frond; This 
is a matter regarding which no definite opinion can be formed, but it is perhaps 
more likely, or at least as likely as not, that the specimen represents the lower part 
of the whole frond and that the asymmetry should be ascribed to the position of 
the fronds in relation to each other. 
Pt. Blasii is known from the Rhaetic at Seinstedt in Germany and from the 
corresponding deposits at Bjuf in Scania, where it occurs in the plant-bearing strata 
u, and 2—4. (Bjuf a, zone with Dictyophyllwm exile. Bjuf 1—3, zone with Campto- 
pteris spiralis. Bjuf 4, zone with Lepidopteris Ottonis.) 
