COLLECTED IN THE SOUTH ORKNEYS. 309 
Only one case of possible reproduction was found (fig. 19); a cell of 
S. polyptera, in which the outline of the wings had become obscure (visible, 
however, as delicate spiral lines in the right-hand portion of fig. 19), con- 
tained a number of elongated protoplasmic masses, in one of which a pyrenoid 
was prominent. This stage is possibly to be interpreted as division of the 
contents of the individual to form a number of daughter-individuals ; if this 
is so, it, of course, constitutes a marked analogy to the probable stage of 
S. antarctica shown in fig. 17. It may be added that the individuals of 
S. polyptera were not uncommonly found in groups of four or five, which 
would quite accord with their being formed by subdivision of а common 
mother-individual. 
Scotiella polyptera is obviously of a more dubious character than 5. ant- 
arctica. While some doubt may justly be felt as to its independence (for it 
might be the zygospore of some form?*), it is impossible to feel quite 
certain of its close affinity to S. antarctica, and further observations may 
warrant its removal from the genus Seotzella. Iu view of the bad definition 
of the wings in all the cells observed, I am inclined to think that no normal 
individuals of S. polyptera were present in my material, and that all the 
forms observed were either preparing for division or passing over into some 
resting-stage f. 
(в) PrEROMONAS NIVALIS, Chod. 
Another form, of which, however, only very occasional specimens were met 
with in the yellow snow material, is represented in figs. 22-24 and 31 of 
Pl. 10. This is almost certainly Chodat’s Pteromonas nivalis i. The indi- 
viduals are of an elongated oval shape and provided with a number of wings, 
which are rather sinuous and have a more or less marked spiral course 
(figs. 22-24). The number of wings has been determined as eight in 
individuals seen from the side, although none were seen in optical section as 
Chodat figures them (his figs. 70 H & J). The behaviour of the wings at the 
two ends of the cells could not be exactly determined, but it would seem 
(fig. 23) as though they projected somewhat at these points so as to give rise 
occasionally to the appearance of a terminal papilla (cf. also Chodat’s figs. 70 В, 
C, К); all the wings appear to run together to а common point. In the 
cell-contents an irregularly shaped, more or less central chloroplast with a 
* І have not, however, met with anything to countenance this view. ^ Lagerheim 
(* Schneeflora des Pichincha,” in Ber. Deutsch. Bot. Ges, x, 1592, p. 529; also * Schneeflora 
in Luleå Lappmark,” in Bot. Centralbl. xvi. no. 11, 1885) refers to oval cells (15 broad 
and 30,4 long) as occurring in red snow from Amsterdamó (Spitzbergen). These cells are 
described as having longitudinal ridges, and may possibly represent the same form as 
5. polyptera or а closely allied опе. Lagerheim, however, regards these cells as probably 
being zygospores of Chlamydomonas lateritia (cf. footnote $ on p. 310). 
T A diagnosis of Scotiella polyptera 13 given on p. 327. 
1 Chodat, * Algues vertes de la Suisse," 1902, pp. 145-146. 
