CHAP, ix.] 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 (antheridid) 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- 



FlG. 101. 



bedded bundles of scalariforrn tissue. There are but 

 six British species, viz., the Fir Club-moss (Lycopodinm 

 selago), the Interrupted Club-moss (L. annotinuvi), 

 the Common Club-moss (Lycopodium clavatuni), of 

 which we give an illustration, the Marsh Club-moss 

 (L. inundatiun\ the Savin-leaved Club- moss (L. al- 



