HALLE, FRUCTIFICATIONS OF CLADOPHLEBIS DENTICULATA. 7 
appears that the species cannot be brought under any of the 
existing families of the Filicinew, such as these have been defined 
on the basis of living forms. Among fossil ferns, the nearest 
analogy as regards the sporangial structure appears to be found 
in Senftenbergia Corpa.' This Paleozoic genus is characterized 
by a pluriseriate apical annulus of thick-walled cells, which is, 
however, believed by STUR to pass over gradually into the thin- 
walled tissue of the lower part of the sporangium. On account 
of this annulus, the species has been referred by most authors 
to the Schizeacee (CORDA, |. c.; ZEILLER?). STUR,’ however, has 
advocated a Marattiaceous affinity, and SOLMS-LAUBAcH,* 
too, considers it as the best plan to include the genus in the 
Marattiacee, although he admits that in so doing the limits 
of that group will have to be considerably widened. Scorr’ 
points out that Senftenbergia may perhaps be placed among the 
Primofilices of ARBER", and SEWARD’ also remarks that it might 
be a generalized type such as occur frequently in Paleozoic 
floras. 
Although the sporangia of the present fronds may be de- 
scribed as recalling in some respect those of Sentftenbergia yet 
there is a considerable difference. In Cladotheca the upper 
zone of thick-walled cells is much less distinct, passing over 
gradually into the tissue of thin-walled cells in the lower part of 
the sporangium, and can not be termed an annulus. Another 
point of difference is in the arrangement of the sporangia. In 
Senftenbergia these are placed singly on the lateral veins, near 
the margin, i. e. as in the recent Schizewacee. In the mesozoic 
fern, as described above, the sporangia are disposed in definite 
sori along the lateral veins. This is a character of some import- 
ance, since it distinguishes the present genus both from Senf- 
tenbergia and from recent members of the Schizwacee. 
At the same time this disposition of the sporangia, as well 
as the absence of a distinct and well-defined annulus, seems to 
' Beiträge zur Flora der Vorwelt, 1845, p. 91; pl. 57, figs. 1—6. 
> Fructifications de fougéres du terrain houiller. Ann. sc. nat., [6], Tome 
16; p. 188; pl. 10, figs. 1—5. — Flore fossile du bassin houiller de Valencien- 
nes. 1888, p. 50. 
* Die Carbon-Flora der Schatzlarer-Schichten. Abth. I. Abh. d. k. k. 
Geol. Reichsanstalt. Bd. 11, Abth. 1. Wien 1885. p. 64. 
* Einleitung in die Palüophytologie, 1887, p. 150. 
? Studies in Fossil Botany. I. p. 287. 
On the Past History of the Ferns. Ann. of Bot. Vol. 20. 1906. 
' Fossil Plants. II. p. 347. 
a c 
