Two Fossil Prothalli. 
3 i 5 
Below are given the measurements of the specimen :— 
Spore. - Length - 1-86 mm. 
Height - 1*38 mm. 
Thickness of Wall - *17 mm. 
Width of Mouth - ’72 mm. 
Prothallus. Length - ’76 mm. 
Height - •24—’38 mm. 
Archegonia. Width - ’062—*08 mm. 
A most striking feature of the preparation, is the development 
of rhizoid-like processes in the interior of the spore. 
These are much branched-filaments, originating chiefly at the 
two points where spore-wall and prothallus meet, and filling the 
entire cavity of the spore with a mass of branches, there being 
many more present than have been represented in the figure (Plate 
VI). These filaments are doubtfully septate; but the presence of 
carbonaceous foreign matter round the filaments prevents any 
certainty about it. They seem to open into small vesicles, masked 
by dirt, at their points of origin. 
Were these filaments absorbing organs of the prothallus or 
not ? If they were, does the specimen represent a type intermediate 
between a free living and an enclosed female prothallus ? 
No absolute connection between the prothallus and any of 
these filaments can be traced, a fact which is a serious drawback 
to the affirmative view. If they are septate, they belong to an order 
of structure uncommon in present day plants, although septate 
rhizoids do occur in the Cyatheacese, and in Dannea .' They are 
very thin-walled and light in colour, agreeing in appearance with 
undoubted fossil fungus hyphse. They present, among themselves, 
considerable differences in diameter, which would not be 
expected in short rhizoids, but is to be found in the old mycelia of 
some recent saprophytic fungi. Again, rhizoids are not often 
branched, more especially richly branched as these structures are, 
while this character agrees with the view of their fungal nature. 
Lastly, their apparent origin at the point of junction of prothallus 
and spore-wall is a suspicious character, for, were they intruding 
fungi, this is precisely the point at which entrance would have been 
easiest. It is true that no hyphse are to be found in the sur¬ 
rounding matrix, but it is evident, from an examination of other 
specimens, that hyphse were often preserved in the interior of 
spores (which they commonly enter at the point of dehiscence), 
1 Goebel. “ Organography of Plants,” II, p. 118, 
