COLLECTED IN THE SOUTH ORKNEYS. 311 
(f) CHODATELLA BREVISPINA, F. E. Fritsch. (Pl. 10. fig. 25, 26 ; 
Pl. 11. phots. 3, 5, Ch.) 
А very typical and rather abundant member * of the yellow snow flora 
is constituted by spiny ellipsoidal cells, which appear to belong to a new 
species of Chodatella, which may be styled С. brevispina (РІ. 10. figs. 25, 20). 
The cells of this species are discoid and about 18 р long and 12 р broad, 
and are covered all over their surface with uniformly distributed spines. 
The latter are very short, and, asa general rule, do not project beyond the 
surface for a distance greater than twice the thickness of the wall ; they are 
mostly rather delicate, but occasionally individuals bearing coarser spines 
were to be found. All the spines on a given cell are generally of about the 
same length, although sometimes slight differences are noticeable. The cell- 
a dark- 
looking outer (probably cuticular) layer and an inner much lighter layer. 
There appears to be a single chloroplast, although I do not feel certain of 
this; a pyrenoid was not observed. Large quantities of fat are almost 
membrane is colourless and consists of two well-marked portions 
always present in these cells. In the majority of cases two more or less 
rounded masses are found, one at each end of the cell and separated by 
a central mass of granular protoplasm in which a considerable amount of 
starch frequently occurs (fig. 26). Often one of these two fat-masses is 
considerably larger than the other, and occasionally only one large mass is 
present at one end of the cell. In some individuals, lastly, the fat pre- 
dominates to such an extent that only a small amount of granular protoplasm 
ап be distinguished, all the remaining part of the contents being obscured 
by the accumulation of fat (fig. 25). 
The greatest difficulty in the way of a satisfactory determination of this 
form as a species of Chodatella lies in the absence of all reproductive stages. 
In Chodatella f reproduction is effected by subdivision of the cell-contents to 
effected by small fusiform zoospores, and on the possibility of the cells containing several 
chloroplasts without pyrenoids (see doe. cif. p. 169). It does not appear that the last of these 
observations is correct, the others have already been criticised above. 
Wille suggests that the oval cells provided with longitudinal ridges, referred to by 
Lagerheim as having been found in red snow from Amsterdami (Spitzbergen) (cf. foot- 
note * on p. 311), were individuals of Pteromonas nivalis. As stated in the footnote on 
р. 911, I am of opinion that they may belong to the genus Scotied/a, but it hardly seems likely 
that they represent Pteromonas nivalis, The rather vague description points more to a form 
like Scottella polyptera. 
Until we know more about the movement referred to by Chodat, it seems advisable to 
leave Pteromonas nivalis in its present genus, 
* This form is much commoner than Scotiedla antarctica, but, owing to its smaller size, 
not nearly so striking. 
+ E. Lemmermann, “ Beitr, z. Kenntn. d. Planktonalgen, I,” in Hedwigia, xxxvii. 1898, 
p. 309; Chodat, * Algues vertes de la Suisse,’ 1902, p. 191. 
LINN. JOURN.—BOTANY, VOL. XL. Vi 
