Key to the Families 



1. Cells solitary or in false dendroid colonies, attached by stalks or fine 



thread-like stipes to larger algae and microfauna chlorangiaceae 



1. Cells not as above; free-floating or adherent - 2 



2. Cells ellipsoidal or fusiform-- coccomyxaceae 



2. Cells spherical ^ 



3. Cells bearing pseudociha (frequently discerned only with difficulty); 

 usually united in definitely shaped gelatinous colonies, macroscopic 

 or microscopic; individual cell sheaths rarely present and if present 



may be scarcely visible tetrasporaceae 



3. Cells not bearing pseudociha; solitary or united in amorphous gela- 

 tinous masses; individual cell sheaths usually clearly visible... palmellaceae 



FAMILY PALMELLACEAE 



These plants have spherical or ovate cells united in amorphous or 

 sometimes definitely shaped colonies. Individual cell sheaths (if 

 present) are clearly evident and are usually lamellate. Although 

 some colonies are spherical and free-floating, others are tubular or 

 bullate and adherent, or entangled among other algae. In one genus 

 (Asterococcus) the chloroplast is stellate, but in general it is parietal 

 and cup-shaped. In 2 genera the sheaths are much lamellated and 

 are deposited as mucilaginous secretions about the cell more on one 

 side than on others so that the cell comes to He excentrically in the 

 investment. Sometimes this may result in the formation of branched, 

 gelatinous strands. 



Key to the Genera 



1 . Cells solitary ^ 



1. Cells arranged to form colonies or famihes v^^hich may be definite or 

 indefinite in shape - "^ 



2. Cells with a stellate chloroplast or with radiating strands from a 

 common center.. .- Asterococcus (in part 



2. Cells with a cup-shaped, parietal chloroplast Gloeocystis (in part) 



(see also Urococcus) 



3. Cells grouped to form amorphous colonies 4 



3. Cells grouped to form colonies of definite shape, spherical 



clusters, or tubular arrangements --" — : — ; 



4. Colonies of macroscopic size, amorphous masses, adherent; cells single 



or in pairs within a copious mucilage; cell sheaths confluent Palmella 



4. Colonies of microscopic size; cell sheaths definite, usually 



lamellate...... ..-..- -- - -- Gloeocystis ( in part ) 



5. Colonies spherical — — --: — 



5. Colonies elongate and tubular, forming false filaments Palmodictyon 



6. Chloroplasts stellate Asterococcus (m part) 



6. Chloroplasts parietal 



7. Sheaths of cells definite, often lamellated; colonial mucilage 



lamellate Gloeocystis ( in part ) 



7. Cells without sheaths, colonial mucilage homogeneous Sphaerocystis 



[82] 



