Howe: Phycological studies 513 



Plate 20. Analheca dichotoma 

 A photograph of a portion of the type specimen (La Paz, Vives 7), a little 

 more than one third of the natural size. 



Plate 30. Gracilaria Vivesii 

 A photograph of a portion of the type specimen (La Paz, Vives 2oe), about 

 four fifths of the natural size. 



Plate 31. Fauchea Sefferi 



A photograph of portions of the type specimen (La Paz, Vives lie), natural size, 

 showing marginal cystocarps, etc. 



Plate 32. Fauchea (? ) mollis 

 A photograph of portions of the type specimen (La Paz, Vives 18a), natural 

 size. 



Plate 33 



1-5. Gracilaria Vivesii 



1. A cross section of the thallus of an antheridial plant. 



2. Surface of antheridial plant. The figure was drawn from a fragment soaked 

 out in water and mounted in glycerin, in which medium the boundaries of the 

 gelatinous walls of the vegetative cells cannot be seen with sufficient distinctness 

 to be drawn accurately. In this mature condition of the antheridia, the gelatinous 

 outer wall shown in fig. 3 as covering the antheridium has mostly dissolved away 

 and the spermatia occupy shallow cavities in the cortex. 



3. A vertical section through an antheridium, which appears to arise through 

 the transformation of the two outer layers of cortical cells. 



4. 5. Young antheridia and adjacent vegetative cells in surface view. 

 Figure i is enlarged 57 diameters; 2-5, 345 diameters; all from the type speci- 

 men ( Vives 2oe). 



6. Fauchea (?) mollis 

 A cross section through the thallus, enlarged 57 diameters. 



7. Cladophora MacDougalii 

 An apical portion of one filament and a fragment near the apex of another, 

 enlarged 11 diameters. 



Plate 34. Halymenia actinophysa 



1. A cross section of the thallus, partially diagrammatic. The figure was 

 drawn from dried material soaked out in water and mounted in glycerin, under 

 which treatment the outlines of the various Ftructural elements, particularly of the 

 large cells of the subcortex, are less distinctly visible than indicated in the figure. 

 The larger cells are often so flattened, collapsed, or translucent that the medulla 

 commonly appears relatively broader and the cortex thinner than represented; and 

 the medulla is often less compact. 



2. A fragment from the cortex and subcortex, showing anastomoses of the sub- 

 cortical cells, etc. 



3. Another fragment, showing other forms of cortical cells and their relations 

 to the subcortex. 



