Macroglossum Alidae , Copeland . 653 
in the leptosporangiate Ferns. The larger prothalli (e. g. PI. XLVI, Fig. 5) 
are so much like a thallose Liverwort in appearance that it is necessary 
to make a close examination before their real nature is apparent. The 
presence of the old archegonia upon the ventral surface, however, can 
usually be easily demonstrated. 
The younger prothalli show the familiar heart-shaped form, with 
a deep sinus, which becomes much less evident in the older stages and may 
become quite obsolete. 
There was no opportunity for studying the germination of the spores 
and the early stages of the gametophyte, but it is highly probable that they 
would agree closely with those of Marattia and Angiopteris, described in 
detail by Jonkman. 1 
PI. XLVI, Fig. 1 shows the youngest stage collected by the writer. 
This was 5 mm. in length, with a deep sinus in front. The posterior part 
was much narrower and the thickened midrib was confined to the anterior 
broader portion. The bottom of the sinus was occupied by a row of 
marginal initials of the usual type, and the first antheridia and archegonia 
had already been formed. The antheridia are developed first and are 
borne both upon the upper and lower surfaces of the thallus. On the upper 
side they form a median group a short distance behind the growing point 
of the prothallus, while on the lower surface they form two small groups 
on either side of the midrib. The group of young archegonia occupies the 
centre of the midrib between the two ventral groups of antheridia and the 
apex of the thallus (Fig. d). 
The older prothalli (PI. XLVI, Figs. 3-5) show a less conspicuous 
sinus and may be almost orbicular in outline. In these older gametophytes 
the midrib is extremely conspicuous and its surface covered with great 
numbers of old archegonia which are visible to the naked eye as dark- 
brown dots. Numerous rhizoids are present in the basal region, but 
they are much less developed in the younger parts of the gametophyte. 
The gametophytes are evidently long-lived and may reach a very 
considerable size. The specimen shown in Fig. 5 was nearly three 
centimetres in length. The apex had been injured and from the broken 
surface adventitious buds were forming. This multiplication of the pro- 
thallus by budding is not at all a rare phenomenon among the Marattiaceae. 2 
A true dichotomy of the thallus apex probably also occurs, as i s t does in 
some other Marattiaceae. The gametophyte shown in PI. XLVI, Fig. 7, 
with two nearly equal branches, probably was the result of the dichotomy 
of the original thallus apex. 
1 Jonkman, H. F. : La Generation sexuee des Marattiacees. Arch. Neerlandaises, etc., t. xv, 
1880. 
2 Campbell, D. H. : The Eusporangiatae. Carnegie Institution of Washington, Publication 
No. 140, 1911. 
