Howe : Phvcological studies 103 



18. A sporangium-base, similar to that sliown in Figure 17, in lateral view. 



19. A coronal process wiih seven hairs (including rudiments and scars). 



20. A rare form of coronal process with only five hairs (including rudiments and 

 scars). 



Figure 16 is drawn from «". jj/o (Atwood Cay, liahamas) ; 17 and 18 from no. 

 573^'^ (Castle Island, Bahamas) ; 19 and 20 from uo.jj/2 (Atwood Cay, Bahamas). 

 All of the figures are drawn from decalcified material and are enlarged 150 diameters. 



21. Acetabulum polyphysoides deltoideum 

 Coronal process, decalcified, viewed from above, and showing seven hairs (includ- 

 ing rudiments and scars). Drawn from the type material (Atwood Cay, Bahamas, 

 Howe ^31 1) and enlarged 150 diameters. 



Plate 7 

 1-4. Acetabulum pusiUutn 



1. A mature plant, with lime coating. 



2. A mature fertile plant, decalcified, 



3. A large sterile plant, decalcified. (See Plate 6, Figures 13 and 14.) 



4. A large fertile disc with unusually obtuse sporangia, decalcified. (See Plate 6, 

 Figure 15). 



Figures 1-3 are drawn from the type material (Montego Bay, Jamaica, Howe 

 ^02ga) ; 4, from tio. ^^jj (Mariguana, Bahamas). All of the figures are enlarged 16 

 diameters. 



5-9. Acetabulum polypkysoides 



5. A disc, decalcified, from above, showing twenty-five lightly coherent, obtusely 

 taper-pointed or subrostrate sporangia. (See Plate 6, Figures 17 and 18.) 



6. Sporangia from another disc, natural, the shaded areas indicating the distribu- 

 tion of the lime. 



7. A disc, decalcified, with seventeen free obtuse sporangia, showing also the cor- 

 rugated upper portion of the stipe. 



8. Sporangia, natural, the shaded areas indicating the extent and distribution of 

 the calcification. 



9. More inflated sporangia, decalcified. (See Plate 6, Figure 16.) 



Figures 5-7 are drawn from 710. 5731a (Castle Island, Bahamas) ; 8, from no. 

 502gb (Montego Bay, Jamaica) ; 9, from no. Jjio (Atwood Cay, Bahamas). All of 

 the figures are enlarged 16 diameters. 



10. Acetabulum polypkysoides deltoideum 

 A sterile disc, with seven sporangia, decalcified, from above. (See Plate 6, Fig- 

 ure 21.) Drawn from the type material (Atwood Cay, Bahamas, Howe 5JI1) and 

 enlarged 16 diameters. 



Plate 8 

 1-7. (jdotea spinulosa 



1. Cross section of the flabellum, natural. The shading indicates rather too much 

 lime for the medullary portions. 



2. Cross-section of the flabellum, decalcified. 



3. The tip of a filament from the apical margin of the flabellum, decalcified. 



4. Portion of a superficial filament from near the middle of the flabellum, decalci- 

 fied. The teeth form a part of the surface-covering of the flabellum. 



