378 THE MICROSCOPIST. 



3. DICTYOTACEJE. Frond cellular, flat, compact. Spores, 

 antheridia (and tetraspores T) in spots or lines (sori) on sur- 

 face. 



1. Haliseris. Frond dichotomous with midrib. 



2. Padina. Frond ribless, fan-shaped, concentrically 

 streaked. Sori linear, concentric, bursting through the 

 epiderm. 



3. Zonaria. Frond ribless, lobed, concentrically striate. 

 Sori roundish, with spores and jointed threads. 



4. Taonia. Frond ribless, 'cleft irregularly, somewhat 

 fan-shaped. Sori linear, concentric, superficial, alternating 

 with scattered spores. 



5. Dictyota. Frond ribless^ dichotomous. Sori round- 

 ish, scattered, bursting through epiderm, or (on distinct 

 individuals) scattered spores. 



3. CUTLERIACEJL Frond cellular, compact, ribless. 

 Dotlike collections of sporanges divided into eight com- 

 partments, and antheridia (?) consisting of chambered fila- 

 ments in groups of curved jointed hairs. 



1. Cutleria. 



4. LAMINARIACE^:. Frond leathery or gelatinous, cellu- 

 lar. Unilocidar sporanges in cloudlike patches, or cover- 

 ing the whole surface of frond ; or multilocular sporanges 

 clothing the whole surface of the frond like an epidermis. 



* Frond stalked, the stalk ending in an expanded leaf- 

 like portion. 



1. Alaria. Leaf membranous, with cartilaginous per- 

 current midrib. 



2. Laminaria. Leaf (simple or cleft) without any 

 midrib. 



* * Frond simple, leafless. 



3. Chorda. Frond cylindric, hollow, the cavity having 

 transverse partitions. 



