100 ZYGOPHYCES. 
spore; nevertheless we have not followed Wittrock in uniting Mou- 
geotia, Mesocarpus, Pleurospermum, Craterospermum, and Stauros- 
permum under the one genus, Mougeotia,, because we think that there 
are sufficient characters to warrant the retention of Staurospermum 
apart from Mesocarpus. If the mode of development in the following 
two species is accurately appreciated, this genus is more allied to Zygo- 
gosin than Mesocarpus. See Archer in Quart. Micro. Journ., 1866, 
p. 271. 
Mougeotia glyptosperma. De Bary Conj. p. 78, t. 8, f. 20-25. 
Sterile cells 7 to 12 times as long as broad. 
Zygospores large, oval, with a thick, firm, yellow-brown 
epispore. 
Sporiferous cells elongated. 
Size. Cells -01--015 mm. 6 to 10 times as long. Zygo- 
spore ‘016X:035 mm. 
Rabh. Alg. Eur. iii. 255. Archer in Quart. Journ. Micr. 
Sci. 1866, p. 65. 
As pointed out by Mr. Archer (Joc. cit.) “ this plant is not truly a 
Mesoca , but in its mode of conjugation more nearly approaches 
certain y apa It is no doubt related, on the one hand to Meso- 
carpus (Hass.) ; like it the endochrome forms a compressed longitudinal 
band, and like it too, the zygospore is formed half-way between the two 
conjugating joints. But, it is distinguished strongly by the fact that 
here the whole cell contents ‘primordial utricles’ and all, of the two 
conjugating joints completely coalesce, leaving the old cell-walls empty, 
in order to form the zygospore; whilst in Mesocarpus the contact of the 
primordial ntricles of the two conjugating cells is not followed by a 
complete coalescence of the two into the zygospore; but by a concen- 
tration of the principal part of the green and solid contents in the con- 
necting canal half-way between the two joints, and the shutting off 
thereupon of the residue of the pale granular contents remaining in each 
parent joint, the denser central portion becoming the spore, and that 
cut off on each side eventually becoming effete and lost. Hence in 
Mougeotia glyptosperma the spore is the actual result of the complete 
fusion of the entire cell contents of the two conjugating joints—it is 
the true zygospore; whilst in Mesocarpus the ultimate spore is a 
daughter-cell, as it were, of the zygospore. Therefore, on the other 
hand, the present plant shows an affinity to Zygnema; but it is, of 
course, completely distinct in the flattened band of endochrome, not 
doubly stellate, as in that genus, not to speak of the extremely different 
comparative length of the cells, which, within the limits of each, is 
constant.” 
Plate XLI. fig. 1. a, sterile cells X 400; b, c, conjugatiag cells with 
zygospores, after De Bary, X 200; d, zygospore, after De Bary, X 400. 
Mougeotia levis. Archer Micr. Journ. 1867 t. 8, f. 1-3. 
Sterile cells twice as long as broad. 
Zygospores broadly elliptic or oval. Epispore thick, brown. 
Sporiferous cells sometimes elongated. 
Sizz. Cells -02--25 mm. Zygospore about -045 x 036 mm. 
Rabh. Alg. Eur. iii. 255. Archer Micr. Journ. 1866, p.270. 
Zygogonium leve, Kutz. Tab, v. t. 18. 
In ditches and pools. 
