72 



THE FERN BULLETIN 



Family 11. — Polypodiaceae. Poly podium, A.s- 

 plemum, Nephr odium. 



Order Hydropteridales. Spores of two kinds, 

 microspores and megaspores ; sporangia without an an- 

 nulus; male gametophyte one-celled, minute; female 

 gametophytes larger, many-celled but little larger than 

 the megaspore. 



Family 12. — Marsiliaceae. Marsilia, Pilularia. 



Family 13. — Salviniaceae. Azolla, Salvinia. 

 Phylum X. CALAMOPHYTA. The Horsetails. 



Chlorophyll-green terrestrial plants, exhibiting two 

 generations in each life cycle, viz: (1) the gameto- 

 phyte, which is small and short-lived, and (2) the 

 sporophyte which is large with roots, leaves and stem 

 and long-lived. Stems of the sporophyte solid or 

 hollow, jointed, erect or creeping, leaves whorled, re- 

 latively small. 



CLASS 22. SPHENOPHYLLINEAE. 



Order Sphenophyllales. Palaeozoic plants of 

 tree-like aspect and dimensions, long since extinct. 

 Stem solid, jointed, bearing relatively small wedge- 

 shaped leaves; sporophylls in cones, each sporophyll 

 with one or two isosporous sporangia. 



Family 1. — Sphenophyllaceae. SphenophyUum. 



CLASS 23. EQUISETINEAE. 



Order Eqisetales. Palaeozoic to recent plants, 

 mostly extinct. Stems hollow, jointed; leaves very 

 small, narrow, and united into a sheath ; sporophylls 

 peltate, in close terminal cones, each sporophyll with 

 several pendant isosporous sporangia. 



Family 2. — Equisetaceae. Equisctum, Equisctitcs 

 (extinct). 



