The seed itself is of a Cycadean type, and radially symmetrical.
Radially placed gaps in the tissue (at first erroneously interpreted as medullary rays, but subsequently more aptly compared to the air-spaces of large Algae) contain very sparse hyphae, which here branch more freely than elsewhere.
Storriei, from the Silurian (Wenlock) of South Wales, described by Barber, there is no sharp differentiation of the two kinds of tubes; they are rarely observed to branch, except in the gaps, which in this species are not radially directed.
De Blainville about 1834, to designate animals the organs of which were disposed radially about a centre.
A comparison of these various types would appear to indicate that the primitive form of prothallus in the genus was radially symmetrical and contained chlorophyll.