A FERN FORMING A NEW GENUS — ETHERIDGE. 
145 
to belong to Sphenopteris elegans, the cortex of which displayed 
an exactly similar series of thickened horizontal parallel bands. 
Still more recently, he received from ray friend Professor Von 
Weiss, of Berlin, and forwarded to me, a beautiful specimen of an 
exactly identical stem, attached to which are the unquestionable 
pinnules of Sphenopteris elegans. As far as these internally 
structureless specimens affect the question, they suggest the 
possibility that both the species of Heterangiv/ni may also prove 
to be Ferns.” Again, speaking of the two genera already referred 
to, Prof. Williamson remarked* — “ One thing is certain, viz., 
that in their internal organisation they present combinations of 
tissues that find no representatives amongst living plants. Possibly 
they are the generalised ancestors of both Ferns and Cycads, 
which transmitted their external contours to the former, and their 
exogenous modes of growth to the latter types. In considering 
this possibility, we must not forget that in Strangeria we have a 
still living plant in which the stem of a Cycad bears fronds, the 
leaflets of which retain the dichotomous nervation of a true Fern. 
The Strangeria has retained, not only the primitive exogenous 
stem of some ancestral type, in common with its other Cycadean 
relatives, but also the peculiar Fern-like leaflets, which may also 
have come down to it from Palaeozoic times. Hence we have 
here a combination of Fern-like features and of an exogenous 
mode of growth. Such being the case, it need not startle us if 
we have to conclude that a similar cambination existed during the 
Carboniferous age.” On this subject Messrs. Williamson and 
Scott remark conjointly! — <fc Inall cases where the petioles can be 
determined as belonging to Racliopteris aspera , we now know that 
we have to do with the foliage of Lyginodendron ,” thus confirm- 
ing previous conclusions, “ namely, that the leaf would fall under 
the form-genus Sphe7iopteris of Brongniart, as shown by the finely 
cut foliage and the acute angles between the veins. . . The 
mere fact that the foliage of Lyginodendron resembled that of 
certain Ferns is in itself no proof of affinity with Filices . The 
classical case of Strangaria is a sufficient warning against any 
such hasty inference. It must, however, be remembered that in 
the foliage of Lyginodendron we have not only fern-like Jorm and 
venation, but also fern-like structure , whereas in the case of 
Strangeria , a single transverse section of the petiole would be 
sufficient to prove that the plant is no Fern but a Cycad.” 
The form of the leaf in the present fossil is certainly that of a 
fern, but unfortunately the structure is not in a sufficiently good 
state of preservation to warrant any definite generalisations. 
There is certainly no evidence of the existence of palisade paren- 
chyma ; on the other hand the presence of a bifacial structure 
* Phil. Trans. (B) for 1887, clxxviii., p. 299. 
f Phil. Trans. (B) for 1895, clxxxvi., p. 727. 
