50 West & West . — Observations on the Conjugatae . 
Fam. II. — * Temnogametaceae. 
This order, defined as follows, ‘ Ordo novus Conjugatarum , 
conjugatio solum inter cellulas speciatim abstrictas,’ was insti- 
tuted a short time ago 1 to include a West African plant 
differing in a marked way from all the genera of Conjugatae. 
The sole representative plant is Temnogametum he ter osp or urn, 
which has a great superficial resemblance to some species 
of Mougeotia. The vegetative cells are precisely like those of 
the latter genus, each cell being provided with a more or less 
plate-like chromatophore, in which a single series of from one 
to six small globose pyrenoids is embedded. 
The conjugation is remarkable, owing to the fact that the 
reproductive cells are specially cut off from the rest of the 
plant ; they are short, isogamous gametes, being about a 
quarter or a sixth part the length of the ordinary vegetative 
cells, and are cut off at intervals along the filaments. Some 
are cut off singly and others in pairs ; in the former case the 
conjugation is scalariform, in the latter it is lateral. In 
scalariform conjugation the contiguous faces of the gametes 
become swollen, these swellings being merely short, rounded 
conjugating-tubes which finally unite (cf. Fig. 49), their union 
being followed by the bending towards each other and ultimate 
coalescence of the gametes to form a somewhat cruciate zygo- 
spore (Fig. 50). As previously mentioned 2 , this zygospore at 
first sight very much resembles the central cell (or carpospore) 
of the five cells constituting the sporocarp of those species of 
Mougeotia belonging to the section Staurospermeae, but on 
closer examination the four contiguous cells are seen to 
possess their complete cell-contents, and to have taken 
no part in the formation of the zygospore. In the case 
of lateral conjugation, the pairs of cells become a little 
oblique or somewhat swollen on one side and then unite, this 
coalescence giving rise to an obliquely subcylindrical zygospore 
1 West and G. S. West, Welw. Afric. Algae, Journ. Bot., Feb. 1897, p. 37. 
2 West and G. S. West, 1. c. 
