cHaP. 1x.] ABOUT MOSSES AND LICHENS. 139 
the fern. But in Selaginella, the few large spores 
germinate by cell division on one side, and thus pro- 
duce a prothallus, in which are formed a number of 
archegonia. The small spores (axtheridia) now pro- 
duce from their interior spirally-twisted spermato- 
zoids, which enter the embryo cells of the archegonia 
and fertilise it. This becomes developed into a rudi- 
mentary root and stem, with two cotyledons, similar 
to the embryo of most flowering plants. 
Their internal structure is similar to that of ferns, 
and consists of thick-walled cells, in which are em- 
a7, 
WW, 
ig 
bedded bundles of scalariform tissue. There are but 
six British species, viz., the Fir Club-moss (Lycopodium 
selago), the Interrupted Club-moss (ZL. annotinum), 
the Common Club-moss (Lycopodium clavatum), of 
which we give an illustration, the Marsh Club-moss 
(L. tnundatum), the Savin-leaved Club-moss (Z, al- 
