259 
Affinities of Peronema and Diacalpe . 
receptacle. The youngest sporangia, showing merely two or three seg- 
mentation-walls, were found at the apex of the receptacle close to fully 
developed sporangia. There are apparently 95 sporangia in each sorus. 
Three countings gave 93, 95, 97 for different sori. 
The sporangium has a long stalk, scarcely so long as that of the 
sporangium of Peranema , with three rows of cells in the stalk. The 
annulus stops short of the stalk in its insertion (Fig. 22), but in passing 
across the head of the sporangium it twists slightly to one side and then 
back again into the vertical position before reaching the region of the 
stomium. This very slight obliquity of the annulus makes it possible 
to discriminate between the two sides of the sporangium, a fact referred to 
by Professor Bower (‘ Phil. Trans.’, vol. cxcii, p. 104) : ‘ In Diacalpe the two 
sides are so far dissimilar that it is possible still to distinguish the “ central ” 
from the “ peripheral ” face.’ 
Hairs are sometimes present on the stalks of the sporangia in Diacalpe 
(Fig. 23) as they are in N ephrodium filix-mas. 
The spores in a single sporangium number about forty-eight. Each 
has an exospore and a perispore, attached at certain ring-shaped areas 
to the exospore and forming irregular folds and papillae on the surface 
of the spore. Here the circular pits with papillae in their centres are few in 
number ; the main portion of the perispore is thrown into irregular folds, 
causing its projection into a series of warty protuberances (Fig. 22). The 
spores of Diacalpe are characteristic ‘ aspidioid ’ spores (Hannig, ’ll) and 
quite closely resemble those of N ephrodium filix-mas , where there are only 
warty protuberances on the surface of the spore. In Peranema the flanges 
of perispore are more prominent and numerous than the papillae ; in 
Diacalpe these flanges are almost entirely absent. 
The prothallus has been described by Schlumberger (‘ Flora’, cii, N. F. 2, 
pp. 384 sqq.). On the under surface of the developed prothallus multi- 
cellular stalked glandular hairs are present. The stalk is composed of two 
or three cells, the middle one often showing a longitudinal division. The 
presence of multicellular hairs is a characteristic of the prothalli of the 
Cyatheaceae (Heim, ‘Flora’, lxxxii, 1896, pp. 360 sqq.). Schlumberger 
remarks for Diacalpe (p. 385) that ‘in many cases, where the terminal cells 
are not developed as glands, these structures cannot be distinguished from 
the multicellular hairs of the Cyatheaceae 
The antheridium of Diacalpe has a segmented lid-cell, another charac- 
teristic feature of the Cyatheaceae (Bauke, ‘ Jahrb. fur wiss. Bot.’, x, p. 72). 
It is therefore unmistakable that the closest relationship exists between the 
prothallus of Diacalpe and that characteristic of the Cyatheaceae. 
An attempt may now be made to compare the features of Peranema 
and Diacalpe with those of other Ferns, with a view to locating these genera 
