512 Howe: Phycological studies 



ment, in fact, the diameter of the filament commonly suffers a 

 slight diminution at the nodal point ; the cells of the subcortex have 

 substellate anastomosing branches, but the cells are very small in 

 comparison with the corresponding cells of Halymenia actinophysa 

 and they rarely have more than 3 or 4 branches. The cortex of 

 the New Zealand Aeodes nitidissima consists of distinctly anti- 

 clinal moniliform filaments of which the ultimate peripheral cells 

 are, as described by Agardh, decidedly narrower than the sub- 

 jacent cells (" exterioribus conspicue angustatis"); these cells are 

 only i-3m in diameter when viewed from the surface, but in a 

 cross section of the thallus are seen to be about twice as high as 

 broad. It may be remarked that in the specimens from Whidbey 

 Island, Washington, distributed in the Phycotheca Boreali- 

 Americana {no. 946) as Aeodes nitidissima J. Ag., the cells of the 

 cortex may hardly be described as being in distinct anticlinal rows, 

 and the ultimate peripheral cells instead of being conspicuously 

 narrower than those immediately subjacent are of equal width or 

 even broader and have 2-4 times the diameter of the corresponding 

 cells in the New Zealand plant. 



The dried specimens of Halymenia actinophysa adhere very 

 firmly and intimately to paper. The cell walls are so gelatinous 

 and translucent that one gets little idea of the real structure of the 

 thallus by examining an ordinary section in water or in water and 

 glycerin — at least until one has learned otherwise what to expect 

 and look for; but by staining sections or fragments with haema- 

 toxylin and afterwards swelling out the more or less collapsed cells 

 by applying a little potassium hydrate or picric acid, the relations 

 of the parts become manifest. 



New York Botanical Garden. 



Explanation of plates 27-34 



Plate 27. Dictyota Vivesii 

 A photograph of a portion of the type specimen (La Paz, Vives 2), natural size. 

 The stipe is shown towards the lower right-hand corner. 



Plate 28. Scinaia latifrons 

 A photograph of a portion of the type specimen (La Paz, Vives 11 a), nine 

 tenths of the natural size. The cystocarps are visible near the margins in the median 

 portions. See also figure i (in text), which shows a better mounted, though 

 mutilated specimen. 



