74 



THE FERN BULLETIN 



Family 4. — Lepidodendraceae. Lepidodcndron, 

 Lepidophlois. 



Family 5. — Bothrodendraceae. Bothrodendron. 

 Family 6. — Sigillariaceae. Sigillaria. 

 Family 7. — Pleuromoniaceae. Pleuromonia. 



Phylum XII. CYCADOPHYTA. The Cycads. 



Chlorophyll-green, terrestrial plants in which the 

 alternation of generations is obscured by the reduction 

 of the gametophyte to a condition of dependence upon 

 the long-lived, leafy-stemmed sporophyte ; spores of 

 two kinds, borne in sporophylls, the microspores set 

 free, the megaspores retained in their sporangia where 

 they develop gametophytes. 



CLASS 27. CYCADOFILICES. (Pteridospermeae) 



Family 1. — Lynginopterideae. Lyngioptcvis, Mcga- 

 loxylon. 



Family 2. — Medulloseae. Medullosa, Steloxylon. 

 Family 3. — Cladoxyleae. Cladoxylon, Voelkelia. 

 Family 4. — Protopityeae. Protopitys. 

 Family 5. — Araucarioxyleae. Araucaryoxylon. 



CLASS 28. CORDAITINEAE. 

 Family 6. — Cordaitaceae. Cordaites, Dadoxylon. 



CLASS 29. BENNETTITINEAE. 

 Family 7. — Bennettitaceae. Bennettites. 



CLASS 30. CYCADINEAE. 

 Family 8. — Cycadceae. Cyas, zamia. 



CLASS 31. GINGKOINEAE. 

 Family 9. — Gingkoaceae. Gingko. 

 Phylum XIV. STROBILOPHYTA. The Conifers. 



