110 ZYGOPHYCE®. 
narrower, and perfectly elliptical, with abrupt ends. How the spores 
behave when germinating I have not yet had any opportunity of observ- 
ing.” 
‘Thus it appears from the foregoing details that the spores are always 
formed without a preceding act of conjugation. The spore formation, 
therefore, may be regarded as neutral, or we may assume thatas in 
exceptional cases spores may be formed by the instrumentality of a 
single cell, in this ease the exception has become the rule, and the spores 
would then be regarded as parthenospores, and not as agamospores.” 
Under these circumstances of development, Wittrock considers him- 
self justified in proposing the genus Genatonema for the two forms, the 
one Gonatonema ventricosum, on which the above observations were 
made, and the other the species which Hassall described as Mesocarpus 
notabilis. 
Gonatonema notabile. (Hass.) Wittr. 
Sterile cells 8 to 10 times as long as broad, sometimes longer. 
Zygospore, front view cylindrical, side view bent so as to be 
convex on one side, concave on the other, truncate at the ends, 
same diameter as the vegetative cells. 
Size. Cells ‘012-015 mm. 
Wittrock Mesocarpee, p. 16, fig. 14. 
Mosocarpus notabilis, Hass. Alg. 170, t. 46, f. 2. 
Mougeotia notabilis, Hass. Ann, Nat. Hist. x. p. 46. 
Staurospermum notabile, Rabh. Alg. Eur, iii. 261. 
Found in great abundance in some brick fields near Notting 
Hill.— Hassall. 
Here follows the original description by Hassall :—“ Filaments at first 
cylindrical, but subsequently becoming angulated, the angle of flexion 
being situate in the centre of each cell. Cells usually about 8 or 10 
times as long as broad, but frequently longer. Sporangia non-symme- 
trical, a single one being placed in the angle formed in each of the cells.’”” 
We have nothing to add to this description, never having seen the 
plant in question, and are able only to reproduce Hassall’s figures. 
Plate XLIV. fig. 3. a, sterile cells; 0, fertile cells, after Hassall. 
