1914] Setchell: The Scinaia Assemblage 89 



SCINAIA Bivona 



The two particular characteristics of this genus within the 

 Chaetangiaceae are the cystocarp and the epidermis consisting largely 

 of swollen colorless cells or utricles. As at present recognized it has 

 been credited with six species as well as three varieties. In the present 

 account, all these species have been retained and one of the varieties 

 has been elevated to specific rank but has been removed, however, from 

 Scinaia to Gloiophloea. The remaining two varieties remain as in 

 previous accounts because of lack of accessible material for investiga- 

 tion. Five new species have been proposed, and certain plants which 

 have the habit and vegetative structure of Scinaia have been the basis 

 for proposing a new genus on account of differences in the structure 

 of the cystocarp. As represented here, then, Scinaia is a genus of 

 eleven species and two varieties. 



I. Cylindrical, Normally Unconstricted Species 



To this section of the genus three species and two varieties are 

 referred. The members of this section are fairly readily to be dis- 

 tinguished from those of the other two sections, although there are 

 difficulties. In the first place, dried specimens, particularly those dried 

 under pressure, do not fully recover their shape. Such specimens and 

 especially specimens dried under any considerable pressure are not 

 always to be readily distinguished from those in which the frond is 

 naturally complanate. In the .second place, while the characteristic 

 plants are lacking in any regular constrictions and show such only 

 when proliferating after injury, there are two cases, seemingly clo.sely 

 related here, in wliich the forms are constricted. They may be and 

 probably are. however, of only occasional appearance. In spite of 

 these two difficulties, it seems to the writer that this is a natural 

 group, sufficiently sharply delimited to deserve special mention. 



The cylindrical group may be again segregated into two .subgroups 

 of one or two species each, by tlie structure of the utricles or colorless 

 cells of the epidermal layer. In the first subgroup the outer ends of the 

 utricles are convex outwardly and bulge somewhat, giving a superficial 

 view of bluntly rounded polygonal cells not closely packed together, 

 while in the second subgroup, the outer ends of the utricles are 

 flattened and give, in surface view, the hexagonal appearance of 

 honevcomb. 



