222 Rhodora [SEPTEMBER 
Cosmarium scenedesmus Delp. The specimens collected here differ 
from the description and figures of Wolle in two points: surface 
decidedly granular, bases of semicells diverging very much more than 
shown in Wolle’s figure (Pl. LXI, fig. 7). These characters are very 
constant in all specimens seen from this locality and it is very abun- 
dant. Length 30-32 m. Diam. 32-36 w. Isthmus ro p. 
Penium digitus (Ehrb.) Breb. Specimen a little smaller than the 
. measurements of Wolle. Length 228 u. Diam. 54 p. 
Staurastrum pygmaeum Breb. A little larger than the measure- 
ments of Wolle but agreeing in all other points. Difference very 
slight. Length 33 &. Diam. 28 u. Isthmus 11 p. 
Staurastrum dejectum Breb. Diam, 25 p. 
Staurastrum subarcuatum Wolle. Wolle does not give the locality 
where he has recognized this species or the exact dimensions observed. 
The form found, measured: length 32 p, diam. 30 pw, isthmus 12 y. 
= Staurastrum saxonicum  Bulnh. A very little smaller than the 
measurements given by Wolle. Sides in end view distinctly con- 
cave, removing it from S. Azrsu/(um, which it resembles although 
slightly smaller. Maine is the only New England state from which 
this has been reported. Diam. 65 y. 
The following forms were identified in a collection made near 
Stony Brook Station, Massachusetts, the last week in March, 1903, 
by Mr. A. F. Blakeslee. As but very little material was examined 
it will be seen from the following that it was rich and varied in its 
contained forms. No filamentous forms were noted in the material 
examined. 
Closterium acerosum (Schrank) Ehrb. Length 650 pm.. Diam. 
45 p. Very common. 
Closterium lineatum Ehrb. Length 540 m. Diam. 38 p. Slightly 
larger than the measurement of Wolle. Common. 
Closterium cucumis Ehrb. Length 325 m Diam. 50 m. Wolle 
gives size in a comparative way only. ‘The specimen fits the figure 
well and the size as given. Very slight ventral swelling noted. 
Cosmarium speciosum Lund. Length 54 p. Diam. 36 p. Isthmus 
15 a. Chlorophyll with a morulate appearance, of large granules. 
Another specimen measures: Length 47 p. Diam. 32 u. Isthmus 
I3 p. 
Cosmarium broomei 'Thwaites. Length 32 x. Diam, 30 p. Isth- 
mus 9—10 p. Central inflation present, thus separating it from the 
following species. 
