Bd. III: 14) 
TUE MESOZOIC FLORA. 
43 
present, though not a very good one. The more logical course would be to keep 
only Pachypteris, and regard both Thinnfeldia and Scleropteris^ as synon}^ms, but 
this involves such a radical change of the present classification, that it had better 
not be undertaken until the matter has been thoroughly discussed. 
Pachypteris dalmatica F. v. Kern. 
PI. 4, figs. 23-28, 33?, 35?. 
Pachypteris dalmatica^ v. Kerner 1895, p. 39; pi. 2; pi. 3, figs. l, 4: pi. 5, fig. 10. 
'i Pachypteris dimorpha^ v. Kern'ER 1S95, p- 47 i pl- 3 j fig- 2; pi. 5, fig. 8. 
The specimens referred here to Kernel’s Pachypteris dalmatica show a great 
variation; but as there are many intermediate forms, they are best included in one 
species. 
The best specimen is the one figured in pi. 4, fig. 26. It represents a portion 
of a bipinnate frond of moderate size. The rachis is comparatively slender, and the 
pinnæ are opposite, each pair at a fairly great distance from the next. The pinnae 
are linear or lanceolate, tapering gradually from near the base. The pinnules are 
lanceolate, somewhat tapering towards the rachis, but attached to it with a broad 
base. They are decurrent on the rachis; and towards the apices of the pinnæ they 
become somewhat confluent. It is evident that the pinnules have been very thick, 
and the venation is therefore not seen on the impression. 
The other specimens resemble more or less the one described. PI. 4, fig. 27, 
shows a specimen in which the venation is faintly visible. In each pinnule there 
seem to be several fine, diverging veins, but a midrib is not seen with certainty. 
The frond shown in fig. 28 of the same plate is of special interest, as the pinnæ 
are much less dissected than in the other typical specimens. The pinnules appear 
only as lobes of the more or less continuous lamina of the pinna. The uppermost 
pinna to the right is only very slightly lobed, and thereby this specimen comes to 
represent a stage of transition to Thinnfeldia. In this specimen the venation of the 
pinna is of a more pronounced Thinnfeldia-iyyte., consisting of forked or simple 
secondary veins, which are straight and parallel and are given off from the midrib 
at a rather acute angle. Through the dissection of the pinna one or more of the 
lateral veins come on each pinnule. Although this specimen is very different from 
the typical ones in figs. 26 and 27, both as regards the individuality of the pinnules 
and their venation, it is best referred to this species. The specimen shown in fig. 25 
seems to be in some respects intermediate between the one just described and the 
typical one in fig. 26. The pinna seen in fig. 24 has very tapering and acute pin- 
nules, but it belongs no doubt to this species, and so does probably the somewhat 
indistinct specimen in fig. 23. The small fragment shown in fig. 35 should perhaps 
