Pri-FFER ARTICLES 
ULVELLA AMERICANA. 
(WITH PLATE VII) 
Ulvella Americana, n. sp.—This form was found with Nitella and 
(fdogonium near Ann Arbor, Mich., and grew in great abundance 
mthe sides of the glass of a small aquarium in which these alge were 
gtowing, 
Though it was found in shallow fresh water at a great distance 
wee undoubtedly belongs to the marine genus Ulvella, the only 
other known species of which, Ulvel/a Jens, was first found by the 
Mouan brothers in 1859, growing on bits of glass, porcelain, and sea- 
weeds, at a depth of twenty meters in the bay of Brest in France. It 
‘sso been found by Hansgirg in several places in the Adriatic sea. 
The Messrs. Crouan* describe the genus as follows: Thallus green, 
Ssk-shaped, 1-2" in diameter, horizontal, adhering by all its under 
‘urlace, composed at the center of cells round, ovate or angled, 
“pang in a subgelatinous substance, reticulated, and containing in 
ence several sporidia. Toward the periphery the cells change 
hd °r rectangular, are much smaller, separated, and arranged in 
«ag lines either simple or forked at their extremities. A vertical 
ce of the thallus shows the cells to be arranged in almost per- 
Pendicular Series, and filled with green. 
oo to this description De Toni? states that the cells " 
hock. (rarely 21 ») in diameter; also that it reproduces by means : 
and are i These are formed in the central cells, 4, 8, or 16 in WH: 
ille3 ho ieee by the dissolving of the membrane. mea 
to the nated this isa doubtful genus, as he thinks it sc an 
and the a Pringsheimia ; but the structure of the chroma es . 
the name “oie _ gametes must separate it from this genus, 4 
vella will be retained. 
Cro; 
titag frees, Ann. d. Sci. Nat. Bot. IV. 12 2288. 1259- 
i - Sylloge Algarum 1: 148. 1889. 
e i 
1899) Sir & Prantl, Die nat. Pflanzenfamilien I. 2: 105. 1890. 
