THE PHYLOGENY OF THE GENUS BRACHIOMONAS 85 
which I searched vainly at Plymouth in 1920. Nevertheless 
since C. brachyura lacks a red eye-spot and is pointed instead 
of rounded at the anterior end, we may perhaps find more 
suggestion of the origin of Brachiomonas in the species mentioned 
at the beginning of this section, namely, 
CHLAMYDOMONAS CAUDATA Wille 
This very interesting and apparently rare species was found 
June 28, 1920, at Aalesund, Norway, in small rock pools of the 
same character as indicated in the original account in 1903 
(15, pp. 115-118, 135, pl. 3, f. g-11) and my determination of the 
species was later confirmed by Professor Wille, from living mater- 
ial which I carried to him in Christiania. In one pool was a practi- 
cally pure culture, giving an intense green color to the brackish 
water; in another pool close by was a considerable admixture 
of C. subcaudata Wille, which was certainly the most abundant 
species of the region, now as in 1902. Why C. caudata should 
occur in only three or four out of many similar pools is an inter- 
esting question. It was also surprising that it could not be 
found on the English coast, where the conditions appeared to 
be much the same, and where I did find several of the other 
brackish-water species which were associated with C. caudata 
at Aalesund. This species appears not to have been found 
elsewhere than at this original station.* 
The elongated oval posteriorly pointed form of the zoospores 
plex is equally striking; so much so, in fact, as intimated above, 
that upon superficial observation the two species might be 
mistaken for closely related members of the same genus. Ordi- 
narily in active individuals, especially in newly formed zoo- 
spores, the protoplast conforms rather closely to the shape of 
the cell-wall, being merely rounded at the point of insertion of 
* Playfair, to be sure, has reported [Proc. Linn. Soc. New South Wales 43: 
515. 1918] a form found appazently in fresh water of which he writes: 
“The only tailed species of Chlamydomonas; it is impossible to make any 
mistake in the identificacion.” Since, however, Playfair states that his 
specimens lacked pyrenoid and stigma, and his figure shows a distinctly 
different morphology of the anterior portion of the cell, including a different 
position fof the nucleus, there can be no easiretpinse for trying. - identity his 
is brought forward to support the attempt. 
