154 American Quarterly Microscopical Jourtial. 



Multiplying by cell division in the last generation, 



sometimes by swarm-spores, Palmellcce, Ktz. 



■Protococcaceae. 



Cells single, without gelatinous investment, 



spindle-shaped, stalked, fixed, Characzutn, A. Br. 



cylindrical, worm-like, crooked, Ophiocytitim, Kg. 



three or four cornered, Polyedrium, Ng. 



Cells together in families, 



cylindrical, fixed, in tree-like groups, Sciadiutti, A. Br. 

 cylindrical, in reticulated large 



masses, Hydrodictyo7i, Roth, 



elliptical, with points, bound together 



in series, Scenedesmus, Meyen. 



cells in single layers, or two or more 



strata, discoidal families, Pediastrian, Meyen. 



club-shaped, Sorastriim, Ktz. 



roundish, polyhedric, in hollow balls, Ccelastrum, Ng. 



quadratic, in cubical families, Staurogenia, Ktz. 



I. FAMILY. PROTOCOCCACE.5. 



Propagation by division of the cell contents into large and small 

 parts, which form swarm-spores. 



[Unicellular, living single or in families. Both macrogonidia and 

 microgonidia are produced ; the first oblong, with two cilia, grow into 

 new plants, the second into resting-spores.] 



1. Gen. Characium, A. Br. Cells long, t.^<g or spindle-shaped, 



stalked, growing attached to other plants, ends colorless. 

 Swarm-spores produced by repeated division of the cell 

 contents. [A doubtful genus. Very likely these plants 

 are stages in the development of others.] 

 Ch. minutum, A. Br. and others. In standing water on filamen- 

 tous Algae. 



2. Gen. Ophiocytium, Xg. Cells cylindric, bent, worm-like, 



with a little point on one end. Swarm-spores eight. 

 O. apiculatuui, Ng. Swimming free in ponds and ditches. 



3. Gen. Folyedriinn, Xg. Cells 3-4 angled with thorny points 



on the angles. 

 F. trigo/ium, X. and P. tetragonum, X. Swimming free, single, 



in swamps and ditches. 

 \P. etiorvie, De Bar\-. This is the only species known in America ; 

 found in Florida. Frond irregular or quadrate, spinous, end view 3-4 

 lobed, lobes more or less emarginate or bifid with simple or branched 

 spines.] 



4. Gen, Sciadiiofi, A. Br. Cells cylindrical, fixed with stalk- 



like base, above single or ramified. Swarm-spores 6-9. 



