84 THE PHYLOGENY OF THE GENUS BRACHIOMONAS 
plura praebente: puncto rubro (stigmate) ioe prope pyre- 
noidem sito: nucleo ad latus oppositum cellulae intra partem 
ovohanphow excavatam complexo: ciliis binis ca. 4% breviori- 
bus quam cellula instructis. 
Propagatio fit per cellulae vegetativae impigre natantis 
divisionem in 4 vel 8 zoosporas, quae tegumenti scissura erum- 
punt. Praeterea aplanosporae, primo virides, postea paulatim 
ad colorem fulvum transmutatae, per contractionem protoplasti 
in massam globosam ad cellulae partem anteriorem, ut in B. 
abmurne: effictuntur 
Generatio fit per c copulationem gametarum inter se subae- 
u 
longioribus praeditae, quaeque per divisionem cellulae vegeta- 
tivae protoplasti etiam in 32 individua parturiuntur. Zygo- 
sporae globose, tegumento levi vestitae, diametro ca. 12 
Longit Spooner veg. 30-48, lat. 18-24. Longit. ganic 
tarum 13-15n, t. 6-8,; longit. ciliorum ca. 
Hab. in oe lacunarum saxearum a Gcelcia Aalesund, 
Norway, 28 June, 1920; Cullercoats, Northumberland, England, 
19 July, 1920; Plymouth, England, 11 August, 1920. 
Because of the fact that unarmed individuals appear in 
older cultures of B. submarina, one might be tempted to inquire 
whether B. simplex is merely a form of that species. Never- 
theless in the natural pure cultures seen both at Aalesund and 
at Plymouth, B. simplex maintained its characteristic simplicity 
of form from the earliest development of the daughter cells 
to maturity, and even when it was found intermingled with one 
of the other species it showed a distinctive character, parti- 
cularly in the curving of the posterior horn, which rendered 
it always recognizable. Again, the variability of form exhibited 
by this new species might readily suggest for it a hybrid origin. 
We know little of hybridization among algae, but a very inter- 
esting preliminary report of its occurrence in Chlamydomonas 
has recently been published by Pascher (7). It may be remarked 
that Pascher’s heterozygous cells showed great diversity in 
internal organization, while here in B. simplex only variability 
of external form is found. From a careful consideration of all 
the conditions of its habitat and its behavior, I am convinced 
that B. simplex is to be regarded as a distinct species which 
represents the transition from Chlamydomonas to the more 
characteristic species of Brachiomonas. 
There is some resemblance between this species and Chlamydo- 
monas brachyura West (13) a form which developed in a tank of 
seawater sent from Plymouth to Birmingham in 1915, and for 
