82 THE JOURNAL OF BOTANY 
they form truly cylindrical filaments, never being more or less 
disconnected, with rounded peor as in Gleotila contorta. 
2. Ulothrix subconstricta, sp. nov. U. filis angustis, 
elongatis et subrigidis, inter cellulas leviter constrictis, membrana 
cellularum delicatissima ; eee diametro 2—4-plo longioribus, ad 
s levissime dilatatis ; chromatoph 
ance parietali lobata, partem medianam 
cellule limitata, sine pyrenoide. Crass. 
fil. 68-7-9p. (Fig. 6. 
Hab. Tn a pond at King’s Norton, 
Worcestershire. 
This species has been under observa- 
ae is also a very slight constric- 
n between adjacent cells. These are 
A pepe not possessed by any other 
epee of the genus. — ee . 
tay cta. Ay flame ies of somewha fefouelar coe ane ais 
only, x 460. B and C, a “ned to the piel part of the cell, and 
jaw: Gali ‘of two. innit only occupying about two-thirds the cir- 
showing sre charac- cumference of the cell-wall, One or more 
om eee soda ica are present in th 
cuole, and are generally situated in 
the clear polar portions ot os cell. The cell-wall is very thin, 
and there is no A cage of a mucous sheath around it. The 
zoogonidia were observed, and attempted cultures of the 
lga were mikes molt 
XVII.—Tue Genus TetTrapEsMvs. 
The genus Tetradesmus was described by Smith* in 1913 for 
a small Alga differing from Scenedesmus in the grouping of its 
cells. Smith made very caret cultures of this Alga, which he 
named Tetradesmus wisconsinensis, and showed clearly that it 
was not a cultural form of Scenedesmus, but that reproduction 
arrangement of the adult before being set free from the mother- 
cell-wall. Chodat+ has recently placed this Alga in the genus 
pela aS Smith, “ Tetradesmus, a new four-celled ccenobic Alga,” Bull. 
Torr. Sg Club, xxxix Rae rch, 1 
B. Chodat, « M = ss ctachine dW Algues en Culture pure,” Matér. pour la 
Flore eryptogam. Sole iv. Berne, 1913. 
eee 
ois Se edeeesan ee é 
SHG oa ae aaa ges ae SS 
