742 
AZOLLA FI LIC ULO IDES LAM. 
an article by E. S. Crispin 0 describing the opening up of the 
river channel of the Bahr-el-Ghebel by the Sudd Expedition 
of 1901-2 “ There was another very light kind of duckweed 
which covered some of the small open pools, and in the absence 
of a current was a great nuisance, obstructing the steamer by 
constantly fouling the paddle wheel.” The identity of the 
“ very light kind of duckweed ” has not been established, but 
the phrase might apply to Azolla nilotica, which has its home 
in that region of the Sudan. 
Description of Plate. 
Figs. 1 and 2. Microspores with prothallia (p), X 750 diam. 
Fig. 3. Part of massula in section with three spores (s), 
X 290 diam. 
Massula, x 90 diam. 
Three hooked hairs (glochidia), each with a septum 
below the barb, X 290 diam. 
A multi-septate glochidium of A. caroliniana (after 
Strasburger). 
Two sori, male (m) and female (f), x 12 diam. 
Macrospore with six adherent massulae, X 45 diam. 
Section of macrospore ; (s c) spore cavity ; (p) pear- 
shaped body ; (m) massula ; (a) resting cells of 
Anabaena ; X 67 diam. 
External view of germinating macrospore, X 35 diam. 
Section of ditto ; (s c) spore cavity ; (p) pear-shaped 
body; (pr) piothallium ; (cot) cotyledon; (m) mas- 
sula ; X 67 diam. 
Resting celk of Anabaena, X 750 diam. 
Section of upper part of pear-shaped body showing 
filamentous outgrowth, X 290 diam. 
Section of leaf from immature plant ; (d 1) dorsal 
lobe ; (v 1) ventral lobe ; (a) cavity with chains of 
algal cells and pore (p) ; (s) air spaces ; (h) the so- 
called unicellular hairs typical of this species ; 
x 45 diam. 
Three imbricated leaves of an immature plant, X 12 
diam. 
Two divergent leaves of a mature plant, X 12 diam. 
Anabaena Azollae, X 500 diam. 
Young sporophyte, showing cotyledon, stem and 
first root, x 64 diam. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
Fig. 7. 
Fig. 8. 
Fig. 9. 
Fig. 10 
Fig. 11 
Fig. 12. 
Fig. 13. 
Fig. 14. 
Fig. 15. 
Fig 
Fig. 
Fig 
16. 
17. 
18. 
6 Geograph. Journ., Vol. XX. (1902), p. 324. 
