297 
This resembles Staurastrum bientanum Rabh. var. connectens 
Boldt, but is much smaller, and lacks the short spines near the 
base of the semi-cells. It seems to be a true Cosmarium. It re- 
sembles C. zxflatum Wolle, differing chiefly in length of cell and 
curvature of the sides. Wolle’s figures are not aiways accurate, 
and it may be that this is a form of his species. 
COSMARIUM DISPERSUM n. sp. Fig. 109. 
Size,medium. Length and breadth about equal. Sinus deep, 
narrowly linear. Semi-cells semi-circular, with the apex some- 
times slightly flattened. Margin gently undulate with about 
eighteen elevations, often less distinct toward the apex. End view 
elliptical ; side view nearly circular. Two pyrenoids in each semi- 
cell. Membrane finely punctate. Diam.=40-44 4; length=4o p; 
thick.=20 1; isth=11y. Found in material from Baton Rouge, 
La., and from Meredith, N. H., at about the same time. Type 
(from Louisiana) in herb. Johnson, 347. 
BOTANICAL LABORATORY, UNIV. OF MICHIGAN. 
Description of Plates 232 and 233. 
(Reduced one-fourth in Photographing.) 
a=front view, vertical view, c—side view of cell. 
. Penium annulare West’ 560. 
F. cylindrus (Ehrb.) Breb., var. Silesiacum Kirch. 750. 
. Closterium Cynthia De Not. X 560. 
. C. tumidum nov. nom. < 560. 
. C. abruptum West « 560. 
C. angustatum Kiitz., var. clavatum Hast. 320. 
C. maculatum Hast. < 320 (a semi-cell). 
. Gonatozygon asperum (Breb.) Cleve. X 320, @ 759. 
. G. aculeatum Hast. < 320. 
. Xanthidium antilopaeum Kiitz. forma Favanicum Nordst. 560. 
. X. concinnum Arch., var. Boldtianum West. % 759. 
Arthrodesmus Michiganensis, n. sp. X< 560. 
- Luastrum Sibiricum Boldt. 750. 
. Micrasterias Nordstediana Wolle. 320. 
15. Staurastum Reinschit Roy. < 750. 
. Cosmarium granatum Breb., var. subgranatum Nordst. % 560. 
C. Paulense (Borgesen). < 759. 
C. Turpini Breb., var. podolicum Gutw. > 750. 
C. dispersum n. sp. X 750. 
C. Raciborskii Lagerh. > 750. 
. C. tetragonum Naeg., var. Lundellit Cke. X 750. 
C. guadrum Lund, forma. > 750. 
Pw hb 
Cor an 
ttt ttt 
Pw by HO 
2 eee « y 
Se ee 
