242 ULOTHRICACEAE AND CHAETOPHORACEAE 
Wittrock, V. B. Om Gottands och Olands Sótvattens-alger. Bih. 
Kong. Svensk. Vet. Akad. Hand. 1': 1-72. fl. 1-4. 1872. 
Om Snöns och Isens Flora. Nordenskiöld’s Studier och Forsk- 
ningar. A4 3. 1883. 
Wood, H.C. A Contribution to the History of the Fresh-Water Algae 
of North America. Smithsonian Contributions to Knowledge. 
1872. 
Description of Plates 
outlines of the drawings were made by means of a Leitz camera lucida and 
the details filled in by careful reference to the specimens. Three combinations were 
, namely, Leitz ocular 3 with bo برو‎ te de oil immerson, ocular 3 with objective 7, 
and VC 1 with objective 7, and the drawings thus made reduced one half in repro- 
duction, so that the actual Vieni of the figures are 575, 350 and 255 diameters. 
Most of the drawings were made from preparations made by the Flemming-chromic- 
alum method. For convenience in identifying the material سیگ‎ which the drawings 
were made, numbers of collections corresponding to those in the text, and the pages on 
which the descriptions appear are appended. 
PLATE 20 (magnification 575 : I) 
I. Ulothrix zonata. Lower rhizoid-like portion of a filament (381), p. 14 
و‎ rtion of the same filament. This specimen corresponds to U. 6 
En. but many filaments of the same material have lower cells differing little in 
diameter from the upper cells, showing that this is an accidental variation. 
: A young filament with — cells (594) 
. Formation of zoöspores, cuated eiie: a motile zoóspore (594). 
۰ 6. Ulothrix tenuissima, tikes of two filaments (535) ; distinguished from 
small pepe of U. zonata chiefly by the shortness of the cells, p. 149. 
. Ulothrix flacca. Apical, middle, and rhizoidal portions of the same fila- 
ment (533) P. 155. 
PLATE 21 (575 : 1) 
1,2, Ulothrix implexa. Vegetative filaments (570 A), p. 154. 
o filaments showing diferent condition « the 
. 15 
-7. Ulothrix variabilis. Vegetative filaments (557, 574), p. 152. 
8,9. Stichococcus marinus. Contrast chromatophores with those of preceding 
49). 
ing rock, in which akinetes seem to be formin 
ng. 
e S 4,1 2 uc ود‎ Jlaccidus. Zoösporiferous filaments and motile zodspores 
18), p 
16, ch nF fil ts sh 
ng varying proportions of the cells (536, 315)- 
PLATE 22 (575:1) 
I. Stichococcus bacillaris. (637), p. 160. 
2, 3. Stichococcus bacillaris forma مق سوا‎ (550, 534), p. 160. 
