227 



FAM. XII. SCYTONEME^E. 



Char. Algae for the most part branched, rigid) or flaccid. 

 Cells globular or compressed. Colour either a dark olive 

 or a vivid oeruginous green. 



The Alga described in this family form two very distinct 

 sections ; the first section embracing those species which are 

 characterized for the most part by a rigid cartilaginous habit, 

 globular cells, a black or olivaceous colour, being lustreless 

 in drying, and the second division including species which are 

 not of a rigid habit, but whose filaments are flaccid, cells usu- 

 ally cylindrical, and colour a vivid green. The species of this 

 last section Kiitzing makes the type of his order Paraspermece, 

 an order characterized by its lateral sporules, and including 

 Lyngbyaceee and Calothricece, families which follow in his 

 arrangement the Scytonemece. 



Section i. STIGONEMEJE. 



22. STIGONEMA Ag. 



Char. Filaments tufted, branched, of irregular diameter, car- 

 tilaginous. Cells moniliform, arranged in transverse lines. 



Derivation. From crrvywv, dotted, and vyfia, a thread. 



There is scarcely any necessity for this genus: the species 

 described in it would form a natural section of the genus 

 Hassallia. 



1. STIGONEMA ATROVIRENS Ag. 

 PL LXVI. Fig. 1. 



Char. Filaments tufted, coarse. Branches slightly divided, 

 subacute. Rings mostly formed of three cells. 

 Q 2 



