394 BULLETIN OF THE UNITED 
EXPLANATION 
PLATE I. | 
I. Chlamydomonas gracilis Snow. 
1,2. Motile cells. 
3. Gamete (7). 
4. Copulation of gametes’. 
I. Chlamydomonas communis Snow. 
1-3. Motile cells. 
. Chlamydomonas globosa Snow. 
1-5. Motile cells. 
. Scenedesmus bijugatus var. flecuosus Lemm. 
1. Cenobium of 82 cells. 
2. Resting stage. 
. Staurogenia apiculata Lemn. 
1. Compound ccenobium of 64 cells. 
2. Compound ccenobium of 16 cells, showing 
gelatinous envelopeas brought out by tan- 
nate vesuvine. 
3. Mass of cells from .05 per cent Knop’s solu- 
tion. 
4. Single ccenobium in early stages of repro- 
duction, taken from an organic solution. 
(a) Nucleus. (b) Pyrenoid. 
5. Single coenobium. 
6. Diagram showing relative position of nuclei 
and pyrenoids in young coenobia. («@) Nuc- 
leus. (b) Pyrenoid. 

7. Membrane of a ccenobium after daughter 
eccenobia have been liberated. | 
8. Cell showing nucleus and pyrenoid, 
(a) Nucleus. (b) Pyrenoid. 
’ PLATE II. 
VI. Fusola viridis Snow. 
1-4. Different stages in process of division. 
(a) Ruptured membrane of mother cell. 
83. Typical cells. 
VII. Oocystis borgei Snow. 
1. Single cell showing nucleus, a. 
2. Young cells from a culture in organic 
solution. 
3. Cells after division of chromatophore. 
Taken from organic solution. 
4. Small colony taken from organic solu- | 
tion. : 
5. Single cell from 0.05 per cent Knop’s so- 
lution, showing remnant of mother | 
membrane, b. 
VIII. Chodatella citriformis Snow. 
1. Mature cell seen from side. 
2. Cell seen from end. 
3. Cell showing reproduction. 
IX. 1-4. Plewrococcus regularis Artari. 

1. Complex from the plankton. 
2-4. Clusters from a culture. 
5. Celastrum microporum Niig. 
STATES FISH COMMISSION. 
OF FIGURES. 
PLATE III. 
X. Plewrococcus aquaticus Snow. 
1. Cell complex. 
2. Individual cells before formation of clus- 
ters. 
3. Complexes grown in collodion tubes. 
4. First stages in formation of complexes. 
5. Disintegration of the larger complexes. 
XI. Chlorococeum natans Snow. 
1. Mature cell. 
2. Gonidia formed in 0.2 per cent Knop’ssolu- 
tion. 
3. Gonidia formed in0.4 per cent Knop’s solu- 
tion. 
. Typical zoospores. 
5. Zoospores formed when material is trans- 
ferred from Knop’s solution to organic 
solution. 
6. Germinating zoospores. 
7. First stage in formation of zoospores. 
XII. Botrydiopsis eriensis Snow. 
1. Mature cell. 
2,3. Young cells. 
4. Gonidia formed from nonliberation of 
zoospores. 
3. Zoospores. (Free hand.) 
6. Germinating zoospores. 
7. Zoospores before liberation. 
XII. Botrydiopsis oleacea Snow. 
1,2. Mature cells. 
3,4. Younger cells of different shapes. 
5-7. Different stages in the formation of the 
zoospores. 
8. Zoospores. 
9. Germinating zoospores, 
10-11. Resting condition. 
PLATE IV. 
Chlorospheera lacustris Snow. 
1. Single cells. 
2,3. Complexesarising from division. 
4. Zoospores. 
5. Germinating zoospores. 
6,7. Stages in the formation of the zoospores. 
. Chlorosphera parvula Snow. 
1,2. Complexes formed by division. 
3. Zoospores. 
— 
XIV. 
XVI. Mesocarpus spec. 
1. Normal filament. 
2. Filament under unfavorable conditions. 
XVII. Ce@lospherium roseum Snow. 
1. Typical individual. a. Surface view. 
b. Interior view. 
2. Celospherium (?) showing free dichoto- 
mous gelatinous branches. 
Chroococcus purpureus Snow. 
Showing mode of growth in small clusters 
embedded in gelatinous substance. 
XVIII. 
