KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 5l|. N:o 3. 47 
seems thus to be decidedly Lower and Middle Cretaceous, ranging from the Urgonian 
to the Cenomanian. — Cladophlebis Browniana and Sphenopteris (Ruffordia?) Goep- 
perti are characteristic species of the European Wealden. The former, with which 
the corresponding Patagonian form is probably identical, though a definite determina- 
tion is not possible on account of the poor quality of the material, appears, with 
the exception of a couple of doubtful records of its occurrence in the uppermost 
Jurassic, to be exclusively a Wealden species in the palaeobotanical sense, being known 
from different districts in all the continents, in Europe especially from the Wealden 
formation, sensu stricto. If Cladophlebis Ungeri (DUNK.) WARD is included in it, the 
species would range, according to SAPORTA (1894), up into the Albian. Sphenopteris 
(Ruffordia?) Goepperti is also especially characteristic of the Wealden and is known 
both from the type-distriets of Europe and from strata in Japan and North America 
considered to be of the same age. The species has been found, however, in some 
districts already in the Jurassic — so, for instance, in England, in Graham Land, 
and possibly in North America. According to SAPORTA it reaches as high up as into 
the Albian. The identity of the form described above as Gleichenites cf. micromerus 
with HEER'S species from the Kome beds of Greenland is far from certain; but as 
it appears to come nearer to the latter than to any other known species, the evidence, 
such as it is, would be in favour of a similar age, or Barremian to Aptian (Urgonian). 
The group of forms now considered distinctly indicate a Lower Cretaceous age, 
at least if the Wealden (sens. str.), in accordance with the palaeozoological evidence, 
is referred to this system. As has been remarked above, it is impossible, on the 
basis of the fossil plants, to arrive at any more exact determination of the age within 
the range from the base of the formation up to the Albian. As the Wealden-flora 
continues to a great extent up to the Aptian and even the Albian, the presence of 
typical Wealden species is not opposed to a fairly high position of the plant-bearing 
horizon in the Lower Cretaceous. The occurrence of the Nathorstia-type would, indeed, 
rather seem to indicate a fairly high horizon, since that genus is not known from 
strata older than the supposed Urgonian of Greenland and appears to be especially 
characteristic of the Cenomanian. At any rate, there is nothing, as far as this group 
of plants is concerned, that is in discord with an Aptian age, which would appear 
probable, according to Prof. SToOLLEY'”S treatment of the invertebrates. 
As has been stated in the geological section, the plant-bearing bed at c prob- 
ably belongs to the very base of division 6 and possibly to the transition between 
J and 6. Of the invertebrates identified by Prof. STOLLEY only Silesites desmocera- 
tordes STOLL. and Neohibolites ef. semicanaliculatus BLAINV. sp. are from division 9, 
at Bahia de la Lancha. The former is stated to indicate a Neocomian or Aptian 
age, the latter an Aptian age. There is some doubt as to the position in the series 
of the latter species, but it may be derived from the uppermost part of division 5. 
According to these cephalopods the flora should be regarded as rather younger than 
Aptian. In two different localities, at Arroyo Calafate and immediately south of c, 
a species of ammonite, Ancyloceras patagonicum, was found in strata referred by the 
writer to division 6. This species indicates, according to Prof. STOLLEY, the Aptian. 
