270 JOIIS. HOYi: PKTKUSKN 



lNv<; pri'viously mcntionrcl p\sicc:it:i Kiil/ Div. nr. 2'.) ;m.l U:il). W'A. li")/^ 

 lluTi' is l)ul :i vcrv sli^lil (iilViMi'iu-o in coloiir. 



llu-sc riMiiarks du Ihc i-olours nnliirnlly :i|)i)l,v hul lo dricd iii:iUTi:iI. 

 :in.1 llu'iv is of ooiirse a slij^lU possibilily Ihnl Iho cxnmiiK.rK.n of livin,<; 

 piants mij-lil t^ivt- a (lillVrcnl result, llowcvcr. il is not prohablo as a 

 dilVoroiu-i« in llio livin^ staU' prcsuniably also would liavt- j^iven a dii- 

 loreiu-o in colour in Ihc dricd slate evcn iC Ihe dilVercnce would nol 



have bcon the same. 



As to the iircscnco or absence of cryslals it has lo be rcmaiked liiat 

 this condilion on llie whole must bc eonsidered as a poor systemalic 

 character as it varies to a j^reat exlent accordin^- lo the aj^e of the phint 

 and lurlhermore is absolutely dependent iii)on the cliemical nature of 

 the waler in which the al.-^a <iro\vs. The importance of this character 

 is in Ihe present case further im|)aired by the faet that I in A. lirauns 

 orit<inal si)ecimens of A. pmsina (Hab. Mg. 1572) found numerous small 

 crv'stals which under evolution of air were dissolvable in acelic acid. 



\Ve have still the last distinguishing character betwccn the Iwo 

 species, vi/., the form of the colony. left. Already from the time when 

 A. Braun's original description appcarcd confusion has prevailed as to 

 the actual mcaning of the expressions. and later aulhors have addcd to 

 this confusion. I therefore consider it as granted that .1. prasinct and 

 .A. slaqiiina cannot be kepl apart on the basis of the form of Ihe colony. 

 Hence it ajipears to mc that none of the hitherto mentioned distinguish- 

 ing characters between the two species are of such a nature Ihal lliey 

 carry conviction as to the necessity of keeping the species ai)art. and I 

 have consecpiently set down A. prasiim A. Br. as a simple synonym of .1. 

 slaffniim Spr.j A.' Hr. It is possible that A. />m.s//nj represents the young, 

 vigorous, beautifully green colonred and not yet calci-encrusted specimens, 

 \\±ereas A. sUifi ni na represents the somcwhat older, more brownish co- 

 lonred and often highly calci-cncrusted si)ecimens. 



VI. Coelosphærium Niig. 



Coelosphærium Kiitzingianum Nag. 



Nageli l.Sli) p. 54, tab. I. C. Lemmermann 1910 j). 81. 82 Hg. 2. 



E. Icel. Stagnant water in a branch of Grimsa, among Myriophyl- 

 lum 'lemp 11" ^^le 1914. - N. Icel. Small pond, on decaying parts 

 of piants, GrimstatMr Mvvatn) -"/t 1914. - S. Icel. (irimsta.^ir. mud 

 from dried np lake bottom in a Floi ^^/i 1905 ,H. .1.)! 



.\rea: V 



It is diificult to slate the distribution of this species as it has been 

 constanlly confused with C. Xmjclianum Ung. {(iomphosplurriu Na'neliana 

 Lemm.,. This is, for instance, the case with De-Toni 1907. I'IOO,. 

 Nevertheless the two species are easily distingnishable in that C. Kiitz- 

 mqiamun is not provided with pseudovacuoles. whereas such are deve- 

 loped in C. Kæqelianum Ung. (Bachmann 1907 |). 63). This species is 

 a pronounced plankton form, whereas the former thrives best in mud 

 on the bottom among other algæ or aqnatic piants. I do not believe 

 that any sjjccimen of C. KiUzim/iaiium exists in any of the more pro- 

 minent collections of exsiccata. 



