38 
T. G. HALl.E, 
(Schwed. Südpolar-Exp. 
The characteristic habit is seen in the two counterparts in figs. lo and ii, pi. 4. 
The frond is divided dichotomously into two branches of the same strength. The 
shape of each of these halves is not seen, but they are evidently strongly asym- 
metrical on account of the unusual development of the lowermost outer pinna. This 
starts from very near the point of bifurcation of the rachis and is much larger than 
the other pinnæ, its pinnules being dissected and somewhat like the upper pinnæ. 
The frond looks, therefore, as if it was divided palmately into four segments, the 
two outer ones being much smaller, however, and directed obliquely downwards. 
The pinnules are characterized by their narrow protracted bases and broad rounded 
upper parts. A very characteristic feature is the frequent occurrence, in some pinnules, 
of one or two pairs of small basal lobes, as shown in text-fig. 9 a. The veins are only 
visible in very few cases on account of the thickness of the pinnules. As may be 
seen in text-fig. 9, which represents two typical pinnæ, and in pi. 4, fig. 14 a, which 
shows a pinnule of a specimen probably belong- 
ing to this species, the venation is more or less 
like that of Saporta’s Scleropteris, for instance 
5 . compacta (Saporta, 1873; pi. 48, fig. 3 a; pi. 
51, fig. 8 a). If a median vein is present it is not 
much more marked than the lateral ones. All 
the specimens are sterile. The one shown in fig. 
18 has on the pinnules some small dots which 
might be taken to represent sporangia; but a 
closer examination proves that they are very ir- 
regular and no doubt of accidental nature. 
The question might be raised, whether this- 
frond should not rather be made the type of a new form-genus. It is certainly very 
unlike all other members of the genus Sclcroptcris, and the mode of branching of 
the frond is usually regarded as a character of generic value. But there is the diffi- 
culty that this character, however important, can only be of use in the rare cases 
when the very base of the frond is preserved, and it seems therefore to be the more 
practical course to include this peculiar kind of frond in Scleropteris. If the com- 
plete specimens described here as fronds are regarded as pinnæ of first order, the 
structure would be comparable with that of the Palæozoic Diplotmema-X.y'pç. (cfr. 
POTONIÉ 1892, p. 18). 
The present species does not appear to come very near any other known fossil 
plant. Single pinnæ sometimes resemble somewhat those of the species described 
here as Scleropteris crassa, but are always easily distinguished by the shape of the 
pinnules. The species seems to have been a fairly common one in the Jurassic flora 
of Hope Bay. 
