HIDDEN MARRIAGES 



521 



sporanges, the inner ones microsporanges (fig. 661). A second species, 

 1. hystrix, found in Guernsey, is of terrestrial habit, growing on sandy soil 

 which is only occasionally inundated. In this Order the prothallium is 

 not nearly so precocious as in Selaginella. The megasporange decays and 

 sets free the megaspore, and it is not until several weeks later that the 

 contents become converted into cellular tissue. Then the epispore breaks 

 up by a three-rayed fissure at its apex, and the rupture of the endospore 

 follows, exposing part of the prothallium, which is in this case spherical. 



Photo fty] 



IE. Step 



FIG. 664. SCREW Moss (Tortula subulata). 



A moss common on wall tops and woodland banks. The curved cylindrical capsules are borne on long, 

 bristle-like stalks, and the peristome is spirally twisted so as to resemble a screw. 



An archegone appears at its apex, very similar to that of Selaginella, and 

 if this becomes fertilized no other is produced ; but in the event of failure, 

 others appear until fertilization of one is effected. The microspores are 

 three-sided and ultimately contain long, slender, and spirally coiled 

 antherozoids, which taper to a fine point at each end, where numerous cilia 

 of great length are produced. The swarming period is only a matter of 

 a few minutes, the antherozoids finding their way to the oosphere by 

 the neck canal as in Selaginella. 



