and the Prothallus of Peranema cyatheoides , D. Don. 105 
oblique annulus, the cells of which are continuous past the stalk (loc. cit., 
PL XXIX, Figs. 16 and 19). 
We can now consider how these features of the sorus and sporangium 
affect the systematic 
position alreadyassigned 
(loc. cit., pp. 264-5) to 
Peranema. 
The character of the 
vascular system and the 
structure of the mature 
sorus and sporangium 
led to the conclusion 
that Peranema occupied 
a position intermediate 
between the Cyatheaceae 
and the Aspidieae group 
of Polypodiaceae. A 
basal indusium of cup- 
type is characteristic of 
the genus Cyathea and 
other advanced types of 
the Cyatheaceae (Bower, 
’ 99 , p. 52). In Peranema 
the cup is ‘ developed 
unequally on its two 
sides and contracted at 
its rim, which is turned 
inwards ’ (Davie, T2, 
p. 253). The early stages 
show that it is of the 
Cyathea type, with a 
part of one side of the 
cup lagging behind the 
rest of the indusium (cf. 
above, pp. 101, 102). 
The stalk is apparently 
a late growth, due to an elongation of certain cells of the receptacle 
and superficial layers. The sorus with its basal cup-indusium is certainly 
of Cyatheaceous type. The form of the receptacle — widely dome-shaped 
at maturity — recalls that found among the Gradatae (Bower, Land 
Flora, p. 635). The first sporangia arise commonly at the apex of the 
receptacle ; the subsequent sporangia show clear indications of follow- 
ing in basipetal sequence. But the mature sorus is a mixed one. This 
shows a step in advance of the Cyatheaceae. The sporangium develops in 
the manner of one of the Gradatae (loc. cit., p. 638). The wedge-shaped 
Text-fig. 2. a. A young sporangium, showing a wedge-shaped 
base. The first division-wall is transverse, x 450. b. Another 
form of young sporangium, with a transverse first division-wall, 
x 450. c. A young sporangium, with wedge-shaped base and 
oblique first division-wall, x 660. d. Two young sporangia, 
with oblique first division-walls meeting the lateral walls of the 
sporangia, x 660. e. A young sporangium, of the type shown 
in a, with the second division-wall oblique and meeting the first 
transverse division-wall at its junction with one of the lateral 
walls. x 450. f A young sporangium of the type shown in 
b , with an oblique division-wall succeeding the first transverse 
division- wall, x 450. g. A young sporangium, of the type 
shown in d, with an oblique second division-wall meeting the 
first division-wall, x 450. h. An older sporangium, of the 
type shown in g, with the covering cell of the capsule defined 
and an oblique third division-wall meeting the second wall and 
parallel to the first, x 450. i. A sporangium with the stalk 
and the central cell defined, x 450. 
