FILICES 83 



VI. Barren frond thalloid, cordate ; fertile frond arising from the 

 sinus, simple or dichotomously branched ; sori in patches on 

 the back of the bifurcations. 



2 species in S. East Afr. 34. Platycerium 



Fam. 7. Cyatheaceae. 



A. Involucre at first completely enclosing the sorus, afterwards forming 



a cup by splitting at the apex. Sporangia surrounding the raised 

 receptacle. Arborescent. (Plate 10.) 



1 S. A. species, the largest S. A. fern. 



35. Cyathea 



B. Involucre reduced to a scale underneath the sporangia, the latter 



surrounding the raised receptacle. (Plate 11; Fig. 55.) 

 1 species, the Forest Tree Fern. 



36. Hemitelia 



Fam. 8. Hymen op hyllaceae. 



A. Involucre compressed, deeply 2-labiate. (Plates 8 and 24 ; Fig. 56.) 



7 S. A. species. 37. Hymenophyllum 



B. Involucre cup-shaped, with an entire or only slightly 2-lipped mouth. 



5 S. A. species. 38. Trichomanes 



Fam. 9. Azollaceae. 



1 species, doubtful for S. A. 39. Azolla 



Fam. 10. M arsiliaceae. 



4 species in S. A. (Fig. 57.) 40. Marsilea 



Class II. EQUISETINAE. 



Fam. 11. Equisetaceae. 



1 species in S. A. (Fig. 58.) 41. Equisetum 



Class III. LYCOPODIINAE. 



Fam. 12. Lycopodiaceae. 



A. Sporangia reniform, one-celled, opening lengthwise along the top. 



(Plate 12 ; Fig. 59.) 



7 species in S. A. 42. Lycopodium 



B. Sporangia 3-lobed, 3-celled, each cell splitting down its centre. 



1 S. A. species. 43. Psilotum 



Fam. 13. Selaginellaceae. 



10 S. A. species. (Fig. 60.) 44. Selaginella 



Fam. 14. Isoetaceae. 



2 S. A. species, about 60 others. (Fig. 61.) 45. Isoetes 



