1914] Setckell: The Scinma Assemblage 85 



cells, the central one of each corymb being enlarged and colorless. 

 This is particularly true of Scinaia furcellata but is found to some 

 extent in other species of Scinaia. In extra-European plants, hitherto 

 referred without question, the relation of colored and colorless cells 

 is different, as will appear during the discussion below. Berthold 

 (1882, p. 697) speaks of the development of the colorless outermost 

 layer of cells and says that they do not divide after they are formed 

 but as the thallus develops, the under cells push out through and 

 become enlarged and hyaline. Berthold looks on this colorless layer 

 as a protection against high light intensity. J. G. Agardh (1880, p. 61 ) 

 also treats of this layer of utricles in Scinaia. 



The colorless epidermal cells, or utricles as they may be called, vary 

 in size and proportions in the different species and also as to the 

 admixture or absence of colored cells, affording trustworthy evidences 

 of specific difference, as will be shown later. 



In the new genus, Pseudoscinaia, to be proposed below, the outer 

 layer is made up of utricles as in Scinaia, but in the genus Gloiophloea 

 of J. G. Agardh the outer layer is described as being made up of 

 fasciculate moniliform dichotomo-fastigiate filaments. An examination 

 shows, however, as will be indicated below, that the same cymose- 

 corymbose structure prevails as in Scinaia, i.e., the central cell of the 

 corymb ceases to grow, enlarges, becomes hyaline and thus changes 

 into a utricle. The surrounding cells of the corymb, however, grow 

 on and repeat the process at a higher level, branching corymbosely in 

 turn, forming a utricle in the center, while the lateral branches grow 

 on and finally form a complete series of fasciculate moniliform anti- 

 clinal filaments. The utricles are thereby hidden and usually collapse 

 sooner or later, becoming inconspicuous and often difficult of detec- 

 tion. This is particularly true of the antheridial areas. In cysto- 

 carpic plants, especially when younger, the appearance is much that 

 of Scinaia, except tliat the colored cells surrounding the utricles are 

 unusually numerous. 



At the base, in the disk and the stipe, the structure is more solitl 

 than above in tlic l)ranches and the colorless epidermal cells are prac- 

 tically absent. The hypodermis, that is, the layer or hiyers of colored 

 cells under the colorless "epidermis," varies in number, arrangement 

 and size of cells in llic different species. TIh' number of layers varies 

 from one to three, the size varies considerably, aiul the arrangement 

 in some species is looser than in others. 



Within the hypodermis of the cortex and moi'e or less closely 



