PROGRESS IN PROTOZOOLOGY

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algae by phycologists (Bourelly 1968, Christen sen 1962, 1966).
Subsequently, however, on the basis of electron-microscopic studies
(H i b b e r d 1975, Leadbetter 1972, Leadbetter and M a n t o w
1974), they were removed from among the plants and by implication
from PHYTOMASTIGOPHOREA. Although the choanoflagellates share
certain structural characteristics with the choanocytes of sponges and
of other metazoa (Norrevang and Wingstrand 1970), their
retention in a separate protozoan order appears entirely justified. No one
took issue with this assertion.
The question of BICOSOECIDA Grasse et Deflandre, 1952, appears
more complex. Hall (1953), among others, placed these organisms
among the chrysomonads, and more recently Mi g not (1974) assigned
Bicoeca to this assemblage of pigmented flagellates. He thought that this
group of unpigmented heterokont, lorica-dwelling flagellates might be
appended to the Chry sophy ceae, but, according to Vickerman,
a number of features sets Bicoeca apart from these algae. Among the
structures in question is the long tongue-like appendage (languette)
which arises alongside the two flagella and is supported by a row of
microtubules. Although the languette is somewhat reminiscent of the
heptonema found in Prymnesiophyceae, in Bicoeca it is involved in food
capture. Although the mastigonemes on the anterior coiling flagellum
of BICOSOECIDA are tubular and similar to those found in CHRYSO-
MONADIDA, the anchoring recurrent flagellum, having a fibrillar sheet
and attachment cone is distinctive. It must be also remembered that the
carbohydrate storage product of the bicosoecids is glycogen and not leucosin.
In a subsequent personal communication to me, Prof. Vickerman
stated with regard to BICOSOECIDA: "I do not think they should
be in a separate order if Silicoflagellida (in Honigberg et al. 1964;
Levine et al. 1980) and Ebriida (in Honigberg et al. 1964) and
other chrysomo.nad appendages should. There are certainly enough ultrastructural
features to set them apart."
The unnatural and clearly polyphylectic nature of the order RHIZO-
MASTIGIDA Doflein, 1916 was pointed out by the committee of the
Society of Protozoologists which was responsible for the 1964 classification
scheme. At that time Honigberg and B a 1 a m u t h stated in
a footnote: "The presence of simple mastigonts in trophic stages is the
basis for alignment with Mastigophora rather than with Sarcodina,
while at the same time the concomitant occurrence of flagella and pseudopodia
strikingly illustrates the basic affinities .of generalized flagellates
and amebae (as originally suggested by Pascher 1918). The tendency
for secondary reduction of flagella is observed in numerous representatives
(of the order). The polyphylectic nature of the group is indicated
by the presence of at least two distinct kinds of pseudopodial organiza-
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