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PACIFIC SCIENCE, VoL XII, July, 1958 
tetrasporangial mother cells (Fig. 3 pc). They 
produce two '’cover” cells {a and b in Figs. 
3, 4) (apical and basal), the tetrasporangium 
{Fig. 3t), and finally a third cover cell some- 
what basally. The first two laterally produced 
cover cells curve around over the tetraspo- 
rangium. The third is produced ventrally and, 
likewise, grows over the surface of the sporan- 
gium. Thus the two pericentral cells (dorsal 
and ventral) and the three cover cells cut off 
by each of the two lateral pericentral cells at 
each side (i.e., 8 cells in all) make up the 
outer layers of each fertile mature stichidial 
segment. 
DISCUSSION 
Since "cortication” in our material con- 
sists, in sterile regions, only of pericentral 
cells, the opinion becomes critical as to 
whether or not there are "flanking cells” or 
"cover cells” present, cut off by the pericen- 
tral cell before the tetrasporangium. If there 
are flanking cells, one is inclined to consider 
Cottoniella hawaiiensis a member of the Deles - 
seriaceae, accepting Papenfuss’s (1944: 202) 
statement that, in that family, cover cells are 
cut off only after the tetrasporangium. 
Certainly one "weakly-covering” cell is cut 
off after the tetrasporangium, and the lateral 
pericentral cells produce two cells lateral to 
themselves before the tetrasporangium is pro- 
duced in the same way the flanking cells are 
produced in Platysiphonia. 
The tetrasporangia are somewhat more cov- 
ered over in C. hawaiiensis , and by a more com- 
plicated cover cell system, than in the case of 
Taenioma (Papenfuss, 1944: 195, figs. 4, 14, 
199) or Platysiphonia (Silva and Cleary, 1954: 
e.g., 256, fig. 27), and other similarly simple 
members of the Ceramiales. However, the 
stichidial features are shown here for Cottoniella 
and for tetrasporangial areas of other genera, 
by various authors elsewhere, to be quite 
homologous in structure. Schotter has em- 
phasized already (1951: 287) the similarity be- 
tween the vegetative structure of Cottoniella 
and these two other genera. Especially are 
Cottoniella and Platysiphonia similar in basic 
vegetative structure. 
As regards the sequence of pericentral cell 
formation, it is interpreted as rhodomelaceous 
in all the Cottoniella material we have seen, 
following Naegeli’s (1847, fide Schotter) early 
distinction of this family from the Delesseri- 
aceae on this point. Boergesen’s figures (1919: 
147, fig. 59b, c) lead us to expect this in C. fusi- 
formis , despite his statements to the contrary. 
All in all it appears that Cottoniella is one of 
those simple algae that would some time ago 
have been placed in the Sarcomenioideae 
(Sarcomenieae of authors). The flattened four 
pericentral-celled nature of the stichidia of 
C. hawaiiensis bearing two tetrasporangia per 
segment bespeak of a delesseriaceous affinity 
for Cottoniella , and we are inclined to relegate 
it at present to that family but recognize its 
possible connecting-link nature between that 
family and the Rhodomelaceae. 
SUMMARY 
Study of tetrasporic Cottoniella hawaiiensis , 
a previously undescribed species from Hawaii, 
indicates placement of this genus among the 
Delesseriaceae on the basis of the mode of 
tetraspore production, or intermediately be- 
tween that family and the Rhodomelaceae on 
the basis of weighting and interpretation of 
other features such as flanking cells, cover 
cells, apical cell development, and exogenous 
branches. The appearance of exogenous 
branches as a regular feature and the degree of 
development of the pericentral cell systems 
set the Hawaiian species apart from all others 
in this genus. 
REFERENCES 
Boergesen, F. 1919- The marine algae of the 
Danish West Indies. Part III. Rhodo- 
phyceae. le (Part 5 or Nr. 5). Dansk Bot. 
Arkiv. 3(5): 305-368, 360 figs. 
1930. Marine algae from the Canary 
Islands . . . III. Rhodophyceae. Part III. 
Ceramiales. Danske Vidensk. Selsk . Biol. 
Meddel. 9(1): 1-159, 60 figs. 
