PRI>n\v \TI.I; \i : TIIK SOUTH < - 117 



vegetative repn>duction .!' tlii', form, the threads breaking into two halve*, each of 

 which has at first one |>ointol and n-- rounded end. The stage shown in my fig 

 undoubtedly shows one of tin- product* of such a division. Subsequently, according to 

 Lagerheiin, the round end grows out into a new km- lik>- point. Most of the individuals 

 found in the yellow snow were of narrower dimensions than I .:!_ rli.-im's form, and the 

 cells were ratli-T Linger (fig. 33) ; l>ut filaments were found here and there i|uite agree- 

 ing with /{'ijiliidonema nivale, Lagerb., and there is no reason to regard the forms in 

 the yellow snow as distinct from this species. 



In his recent revision of the green alg Wille 1 includes Lagcrheim's Raphidotiema 

 in the genus R-tphidinm. Kut/.. ( ~ Ai<k-istrode*mus, Corda) ; this is in agreement with 

 Chodat's earlier view.* It seems a little questionable, however, whether this is really 

 warranted. Tin- typical species of the genus Raphidinm are unicellular or colonial 

 forms, in which reproduction is effected by transverse division of tin- contents (frequently 

 into four), followed by elongation of the segments, so that they ultimately come to lie 

 side by side as a munU-r of daughter-individuals within the mother-cell (so-called auto- 

 spore-dtivelopmeut). This has not been observed in Rafkidontma iiiivtle. On the 

 other hand, although septate /^/yi/m/i'<///ix li.ivc In-en described (e.g. A', /iifri'nogerum, 

 'ii'id.. and /.'. nit\tle, Chod.*), the breaking up of the septate individual into two part* 

 by fragmentation is not known for this genus. The NMmUancc of Itnphitlonema to 

 Raphidium therefore appears to l>e purely superficial, and one must agree with 

 Lagerheim's original view,* which regarded this snow alga as a member of the 

 Ulotrichalcs, probably to be included in the Chaetophoraceae ; the peculiar method 

 of vegetative reproduction may, however, indicate a relationship to Stichoroccii*,* and 

 until more is known about Raphidonema its exact position must remain doubtful. 



Very rarely forms were found of the type shown in I'l. I., fig. 34. This shows a 

 single cell of the Rnphidium-typc (diam. 2 n) with a prominent central pyrenoid. 

 This is probably a species of Raphidium, possibly R. pyrenogentm, Chod., which is 

 distinguished by having a pyrenoid, but Chodat's species appears to be much broader. 

 1 have seen too few individuals to be sure of the specific determination. 



Filamentous forms are poorly represented in the yellow snow flora. The most 

 abundant is Uloihrix subtilis, Kiitz., of which relatively short filaments were always 

 to be found embedded among the numerous unicellular and colonial constituents 

 (PL II., phots. 1, 2, U). Next in abundance comes It. uiivtle, I^agerh., which has 

 already been considered. Lastly, very occasional filaments of a broad species of 

 (Edogonium (diam. cell = 20 M) with well-marked caps were observed. 



* Wille, in Bngler-Prmnll, hit \<,,rl. I'l.nxnfam^ X.chtr. . 1 Tail, 9 AbUul., 1909, p. 68. 



* Chodat, " Flora den neigw da col de EcandiM," BtM. Herbier Bourier, iv., 18B8, p. S86. It dow not Mem that 

 Cbodkt'i BnpkiJium nival* u in any way allied to RaplriAmima. 



* Chodat, A Iff** mrttt 4* la SHU*, Berne, 1908, p. 800, fig. ISO. 

 4 Lot, at, p. 693. 



Of. Lagrhim, lae. eil., pp. 693, 694. 



