Bd. III: 14) 
THE MESOZOIC FLORA. 
27 
A diagnosis of the Antarctic form may be given for comparison with Heer’s de- 
scription. 
Frond large, bipinnate; pinnæ long and narrow, at a nearly right angle to the 
slender rachis. Pinnules alternate, lanceolate to oblong, contracted at the base and 
attached at a nearly right angle to the axis of the pinna, pinnately lobed to more 
than half the distance between the margin and the midrib; lobes almost rectangular, 
truncate, obtusely bidentate, with the vein dividing, less than half way to the mar- 
gin, into two branches, passing each to one of the teeth. Fructification unknown. 
This fine frond, which has a breadth in the largest specimen of considerably 
more than 10 cm., is characterized by its open habit due to the very wide angle 
of attachment of both pinnae and pinnules. The chief specific distinction, however, 
is in the shape of the lobes and, more especially, in their truncate bidentate ending. 
(This character is seen in text-fig. 6 c, an enlarged drawing of a portion of a pinna 
from the specimen in pi. 3, fig. 26. The drawing in fig 26 a, pi. 3, is misleading, 
since it represents an abnormal state with only portions of the lobes preserved, on 
account of shrivelling or some other cause.) This same feature is the most impor- 
tant characteristic of Meer’s Asplénium Nauckhoÿianum^ and in other respects, too, 
there is a very great resemblance between the Arctic and the Antarctic specimens. 
The only difference that I have been able to find, after a careful examination of 
Heer’s type- specimens in Stockholm, is that the latter are somewhat larger, with a 
