COLLECTED IN THE SOUTH ORKNEYS. 305 
particularly true of the forms found on the snow (yellow and red snow), but 
applies to a lesse extent to practically the whole of the material ; only in one 
case (samples gathered on Feb. 4th, 1903, from a freshwater pond at an 
altitude of 140 feet between the peaks of Saddle Island, South Orkneys) were 
organisms (species of Chlamydomonas) present, which had evidently been 
preserved in an actively motile condition. For this reason it has seemed best 
to give as complete an account of the material as possible, in the hope that 
subsequent investigations may lead to a better interpretation of some of the 
forms observed. This has been carried out especially in the case of the 
yellow snow flora. 
Some of the numerous resting-stages observed are referable to described 
species of the genus Trochiscia, or at least come verv close to some o£ them ; 
where this was the ease, they have been enumerated under the genus 
Trochiscia (see the systematic part of the paper), although it was thought 
undesirable (except in one case) to establish new species on this basis. It 
can hardly be doubted that some of the species of Trochiscia are merely 
resting-stages of other Algæ, although where a definite course of repro- 
duction has been observed we are. probably dealing with independent forms. 
In the case оЁ the material from the South Orkneys no evidence as to the 
authenticity of Trochiscia-forms was to be expected, since no single case of 
reproduction was observed ; and there was no choice save to record the 
diverse structures noticed as species of this genus. 
On the whole, it is astonishing that, considering the abundance of some of 
the algal forms, only very few reproductive stages were found ; in some cases 
(e. g. the Trochiscias just referred to, Chodatella brevispina) not even an indi- 
cation of division of the individuals was observed, although the material was 
collected during the milder portion of the year (October to March). The 
mean temperature, however, even at this period (as Mr. В. N. Rudmose 
Brown informs me) is only 32° F. It seems therefore as though many of 
these Antaretie forms reproduce only during very limited periods, when the 
conditions are especially favourable. 
As above stated, the freshwater algal floras of Kerguelen and South 
Georgia, as described by Reinsch (Гое. cit.), have a rather different character. 
The following table shows the relative composition of the algal floras of these 
two localities and of the South Orkneys :— 
KERGUELEN. SOUTH Grorara. SOUTH ORKNEYS. 
ao. —— — œ- 
Genera, Species. Genera, Species, Genera, Species. 
Isokontæ (incl. (Edogoniaces) 25 36 (2081.) 17 32 (12 fil.) 17 29(5fil.) 
Conjugate .......... sn 8 12 (7 fil.) 5 20 (1 fil.) 4 56 (2 fil.) 
Heterokontæ .............. хш. 11 11 
Суапорвусее .............. 18 53 5 5 15 18 
Пуаюотасее................ 13 2 10 19 9 15 
Phzo- and Rhodophyce:w .... 2 2 e. 
Totals........ 65 104 38 17 44 68 
LINN. JOURN.— BOTANY, VOL. XL. Y 
