Phytoplankton of the River Thames. 635 
Table illustrating periodicity of Thames Plankton 1 2 3 4 . 
§o 
HO 
W . II 
• o 
o 
8g 
Pt* 
d II 
<V 
Q 
CO . 
on 
2"o 
H xp 
T? LO 
.0 II 
<L) 
CO 
8nO 
-in 
C II 
s 
May 2, 1903 s ; 
t = I2°C. 
CO 
^ ll 
<D 
c 
od 
0\0 
M LO 
<U II 
G - 
G 
»-o 
„ 0 
' 3 
1 — > 
I. Chlorophyceae. 
Scenedesmus quadricauda (Turp.), Breb. . . 
r. 
r. 
i. 
— 
i. 
- 
r. 
rc. 
Pediastrum Boryanum (Turp.), Men. . . . 
rc. 
r. 
i. 
vr. 
i. 
rc. 
rc. 
c 
„ pertusum , Ktz 
— 
— 
i. 
— 
rc. 
rr. 
c. 
„ pertusum, v ar. clathratum , Braun 
rr. 
— 
— 
— 
— 
rr. 
rr. 
— 
C hlamydomonas Braunii , Gorosch. . . . 
r. 
— 
— 
— 
— 
rc. 
— 
— 
Eudorina elegans , Ehrb. 
— 
— 
vr. 
— 
rr. 
r. 
r. 
Pandorina morum , Ehrb 
— 
— 
i. 
— 
— 
r. 
rc. 
Gonium pectorale, Mull. . 
— 
— 
— 
— 
— 
— 
vr. 
- 
II. CONJUGATAE. 
Closterium acerosum (Schrank), Ehrb. . . . 
r. 
— 
— 
— 
— 
— 
— 
vr. 
,, moniliferum (Bory), Ehrb. . . . 
rr. 
— 
— 
— 
— 
rc. 
— 
vr. 
III. Bacillariales. 
Coscinodiscus radiatus, Ehrb 
vr. 
rc. 
Stephanodiscus Hantzschii , Grun 
c. 
rr. 
rc. 
— 
— 
rc. 
? 
Melosira moniliformis (Mull.), Ag. . . . 
rr. 
rr. 
rc. 
rc. 
rc. 
rr. 
r. 
rc. 
,, varians, Ag 
vc. 
vc 5 . 
c 5 . 
c. 
a. 
a. 
rc. 
c. 
Campylodiscus noricus, Ehrb. . 
rc. 
rr. 
r. 
rc. 
rc. 
rr. 
r. 
rc. 
Surirella biseriata , Breb 
c. 
c. 
rc. 
rc. 
rr. 
rr. 
r. 
rc. 
„ ovalis , Br6b 
„ splendida (Ehrb.), Ktz 
c. 
c. 
rr. 
rc. 
rr. 
r. 
r. 
c. 
c. 
rc. 
rr. 
rc. 
rr. 
rc. 
r. 
r. 
Cymatopleura Solea (Breb.), Sm 
rr. 
r. 
r. 
r. 
r. 
rr. 
— 
r. 
Cymbella gastroides , Ktz 
r. 
rr. 
rr. 
rr. 
— 
— 
— 
rc. 
Amphora ovalis , Ktz 
rr. 
rr. 
rr. 
rc. 
rr. 
rr. 
r. 
rc. 
Fragilaria virescens , Ralfs 
vc. 
c. 
rc. 
c. 
rc. 
rc. 
r. 
c. 
Grammonema spec . (long cell = 16 f) . . . 
rc. 
rc. 
rc. 
r. 
— 
— 
— 
— 
Pleurostaurum acutum (Sm.), Rabenh. . . 
r. 
r. 
rc. 
rc. 
— 
— 
vr. 

Synedra Acus , Ktz 
_ 
— 
— 
rc. 
rr. 
rr. 
a. 
1 
„ Acus , var. delicatissima , Sm. . . . 
_ 
— 
— 
rc. 
rr. 
_ 
c. 

„ Ulna , Ehrb. ........ 
c. 
c. 
rc. 
rc. 
c. 
c. 
a. 
rc. 
Asterionella gracillima, Heib 
— 
rc. 
c. 
r. 
— 
— 
— 

Nitzschia sigmoidea (Nitzsch), Sm 
c. 
c. 
c. 
rc. 
rc. 
rc. 
r. 
rc. 
Pinnularia viridis (Ehrb.), Rabenh. . . . 
— 
— 
— 
r. 
— 
— 
vr. 

Pleurosigma attenuatum (Ktz.), Sm. . . . 
c. 
c. 
c. 
rc. 
rc, 
rc. 
r. 
rc. 
,, Fasciola (Ehrb.), Sm 
Tabellaria fenestrata, Ktz 
— 
— 
— 
rr. 
— 
_ 

__ 
- 
— 
- 
rr. 
rr. 
r. 
- 
— 
IV. SCHIZOPHYCEAE. 
Microcystis marginata (Men.), Kirchn. . . 

i. 
_ 
_ 



_ 
Merismopoedia glauca (Ehrb.), Nag. . . . 
r. 
vr. 
— 
- 
- 
- 
— 
— 
V. Flagellatae. 
Euglena viridis , Ehrb 
Phacus pleuronectes, Nitzsch 

vr. 

i. 


_ 
rc. 
r. 
vr. 




r. 
Synura Volvox , Ehrb 
— 
— 
— 
vr. 
— 
— 
rc. 
r. 
1 a. = abundant ; vc. = very common ; c. = common ; rc - rather common ; rr. = rather 
rare ; r. = rare ; vr. = very rare ; i. = isolated. 
2 The weather had only just become cold the day before, having been mild and foggy 
previously ; so that not too much stress should be laid on this temperature. 
3 River high and current very strong. 
4 Added in order to complete table as far as possible, cf. text. 5 With auxospores. 
