PYERIDOPHYTA. 909 
are all of one kind, and aré borne in roundish spore-cases, 
which are generally single on each leaf. 
The Club-mosses are common in the Appalachian region, Canada, 
and northwestward, and all but one of our species belong to the 
genus Lycopodium. Of these may be mentioned the Common Club- 
mosses (L. clavatum and L. complanatum) and the Ground-pine (L. 
dendroideum), all extensively used in Christmas decorations. 
438, The Little Club-Mosses (Order Selaginellacem) re- 
semble the foregoing, but are generally smaller and more 
Moss-like, and have (with few exceptions) four-ranked 
leaves. Their spore-cases occur singly on certain more or 
less modified leaves, which are clustered into terminal 
spikes. The spores are of two 
kinds; the small ones, which are 
very numerous, are generally 
borne in spore-cases in the upper 
part of the spike, while the 
larger ones (macrospores) are 
mostly four in each spore-case in 
the lower part of the spike (Fig. } 
118). fia. 119.—Plantlets of a Little 
Club-moss (Selaginella martensii), 
439, The first stage of the showing cotyledons. I, two plant- 
lets growing from one spore; p, 
Little Club-mosses is almost ob- the first stage (prothallium). I, a 
plantlet separated from the spore; 
literated. When a small spore 7,,700t; Te Jone called the 
germinates, it becomes divided 
internally into a considerable number of cells, one of which 
appears to represent the first stage (prothallium), while all 
the rest form one large antherid, each cell of which pro- 
duces an antherozoid. 5 
440. The large spore likewise produces a very small 
growth, which in this case, however, protrudes a little from 
the ruptured spore-wall. Upon this several archegones de- 
