and the Prothallus of Peranema cyatheoides , D. Don . 107 
ened from the surface of the leaf, to which the indusium remained attached, 
receptacle and indusium were shot out beyond the surface, well below which 
the further elaboration took place. There such extensions and involutions 
as are' figured for one sorus in PL III, Fig. 6 had ample room to develop. To 
conclude the comparison, this parallel between the condition in a mature 
sorus of Peranema and that in a mature sorus of Nephrodium helps to 
strengthen the view that Peranema occupies an intermediate position 
between the Cyatheaceae and the Aspidieae group of Polypodiaceae 
(which includes the genus Nephrodium). 
The Prothallus. 
Schlumberger (Tl) has described the prothalli of Diacalpe aspidioides , 
BL, Woodsia obtusa , Torrey, and W. ilvensis , Br. On the prothallus of 
Diacalpe he found multicellular hairs, mainly on the region of the cushion. 
These sometimes had glandular heads, less frequently were devoid of them. 
Similar hairs were found on the prothalli of Woodsia obtusa , while on the 
prothallus of Woodsia ilvensis glandular hairs, usually on a one- or two-celled 
stalk, were present. 
Multicellular hairs are present on the prothalli of the Cyatheaceae 
(Heim, ’96). Thus the prothallus of Diacalpe resembles that characteristic 
of that family, while the Woodsia prothallus shows a movement from such 
an affinity towards the Polypodiaceae. 
On the prothallus of Peranema glandular hairs are present, both 
on the margins of the wings and on the cushion. Those on the cushion are 
larger than^ those on the wings ; both types are unicellular, and exactly 
resemble the terminal cells of the hairs figured by Schlumberger for the 
prothalli of Diacalpe and Woodsia . Many of the hairs on the cushion are 
placed upon slightly raised superficial cells (PI. Ill, Fig. 7 ) and resemble the 
example figured by Schlumberger from Woodsia ilvensis (loc. cit., Fig. 1 , 
9 ). At the same time there are many which closely agree with the glandular 
hairs which are present on the prothalli of N ' ephr odium Filix-mas (Kny, ’95, 
Taf. XCVII and C). 
From the structure of the antheridia on the prothalli described by him, 
Schlumberger was able to form a series linking the Cyatheaceae with the 
Polypodiaceae (cf. Bauke, ’76, and Goebel, T3). Diacalpe has a divided lid- 
cell in its antheridium ; Woodsia obtusa has a divided lid-cell of two 
unequally-sized parts ; Woodsia ilvensis has an undivided lid-cell. In the 
last species the rupture of the antheridium is brought about by the discharge 
of the lid-cell, just as in the other two. 
Heim ( 5 96) distinguished between the more primitive families of 
Cyatheaceae, Hymenophyllaceae, &c., and the Polypodiaceae on the 
method of rupture of the antheridium. In the former the lid-cell was 
discharged ; in the latter it was broken through (loc. cit., pp. 356 , 369 ). 
Schlumberger points out that in Woodsia ilvensis the remains of the 
