584 Howe: Phycological studies 



KxpiHiiation of plates 23-29 



Plate 23 



1. Avrainvillea levis. Photograph of two dried specimens(«o. jgg6, type — , 

 Cave Cavs, Exuma Chain, Bahamas, 19 F 1905, M. A. H.), natural size. 



2. Halimeda favulosa. Photograph of about one half of one segment of a dried 

 specimen (from no. jgS/, type), magnified sixteen diameters. 



Plate 24. Halimeda favulosa 



Photograph of dried specimen (no. jg8/, type — , Cave Cays, Exuma Chain, 

 Bahamas, 19 F 1905, M. A. H.), reduced to about two-thirds the natural dimensions. 



Plate 25. Cladocephalus scoparius 



Photograph of formalin-preserved specimens {no. 4079, type — , Georgetown. 

 Great Exuma, Bahamas, 24 F 1905, M. A. H.), natural size. The young plant at the 

 right with the truncate apex shows only the beginning of the differentiation of the capit- 

 ulum ; the other two short plants represent later, though still very immature, stages in 

 the development of the capitulum — in one the stipe is furcate above, the two branches 

 again coalescing ; the three largest specimens are typical full-grown plants. 



Plate 26 



1-6. Halimeda favulosa 



1-3. Peripheral utricles, decalcified, in lateral view. 



4. Peripheral utricles with dense granular content (see page 565). 



5. . Peripheral utricles in surface view, decalcified. 



6. Filaments of the central strand, showing mode of union at the nodes. 

 Figures 1—6 are all enlarged 40 diameters and are all drawn from the type material, 



no. jg8/ (Cave Cays, Exuma Chain, Bahamas). 



7. Halimeda tridens 



7. Peripheral utricles, decalcified, in lateral view, X 4°- Introduced for com- 

 parison with H. favulosa. 



8-10. Avrainvillea levis 



8. One of the larger filaments from the flabellum, with dichotomy. 



9. A fiiament of the usual size, from flabellum. 



10. A filament from apical margin of flabellum, with wide-angled dichotomy. 

 Figures 8-10 are all enlarged 150 diameters; 8 and 9 are drawn from the type 



material, no. jgg6 (Cave Cays, Exuma Chain, Bahamas) ; IO, from no. jg66. 



II-20. Cladocephalus scoparius 



11. One of the main branches of the capitulum, showing ramification, natural size. 

 The left-hand side was toward the middle of the capitulum. 



12. A detail of the branching of the capitulum, showing anastomoses, X 2 - 



13. Cross- sect ions of branches of the capitulum, X 4- 



14. Fragment of a branch of the capitulum in surface view with part of cortex 

 removed, disclosing medullary filaments, X 55- 



15. Medullary filament from apex of capitulum, X 55- The branch at the left, 

 now becoming lateral, represents the beginning of the cortical system. 



