36 
T. G. HALLE, 
(Schwed. SüdpoJar-Exp. 
Pachyptei'is. As type for Scleropteris is regarded here A. Pomelii Sap., and to the 
genus should be referred, with this delimitation, only fronds with pinnules of small 
size like the species mentioned and A. dissecta Sap., A. compacta SAP. etc., but not 
forms of the type of Scleropteris Phillipsii Sap., which must be kept in the genus 
Pachypteris. 
Scleropteris crassa n. sp. 
PI. 3, fig. 14; pi. 4, figs. 4 — 9, I2f, 22?. 
Under the specific name of Scleropteris crassa are joined here specimens of a 
somewhat different habit. The extreme forms do not appear to have much in com- 
mon; but the occurrence of intermediate specimens supports the specific identity. 
Fronds lanceolate, with thick, more or less winged rachises. Pinnæ opposite or 
alternate, lanceolate. Pinnules densely set, somewhat confluent, entire, mostly ob- 
lanceolate to oblong, obtuse, very thick. Only traces of a few' veins occasionally 
seen. Fructification not known. 
As typical specimens of this species may be regarded those figured in pi. 4, 
figs. 4 — 9. They represent bipinnate fronds or possibly pinnæ of tripinnate ones. 
Their somewhat asymmetrical development is in favour of the latter possibility but 
the rachises appear, from their remarkable stoutness, more like those of fronds. The 
pinnæ of the present specimens are opposite or, more often, alternate. The former 
seems to be more commonly the case with the upper ones; but also in the lower 
part there is a tendency towards a sub-opposite position, the pinnæ being approached 
to each other two and two, leaving a greater distance to the next pair. The pinnæ 
are more or less decurrent on the rachis. In the upper part of the frond the wings 
thus formed are mostly very distinct, being each sometimes as broad as the rachis 
itself. In the lower part they are often indistinct or wanting; but this is evidently 
due to the fact that the thick rachis has more or less prevented them from leaving 
any impression in the matri.x. The pinnules are somewhat varying in shape, but 
they are generally broadest in the middle or somewhat higher up and taper more 
gradually towards the base, which, however, is mostly broader than in the pinna 
figured in pi. 4, fig. 5 a. The apex is obtuse, but not very broadly rounded. It is 
evident from the aspect of the impressions that the pinnules were very thick; and 
this is no doubt the reason why the venation is so indistinct. Mostly no venation 
whatever is seen; only in a few cases do there appear to be traces of one or a few 
veins. Towards the tips of the specimens the pinnules become gradually more con- 
fluent and the uppermost pinnæ are only slightly lobed or nearly entire (pi. 3, fig. 
14; pi. 4, figs. 5, 7). 
The specimen figured in pi. 4, fig. 22, probably belongs to this species, but 
differs in having more remote pinnæ and shorter pinnules. It evidently represents 
