ARCIIEU — ON PALMOGLCEA MACROCOCCA (kUTZ.). 15 



mon character being the pervading elongate or oblong form of the cells. 

 Amongst these Palmogloea-forms, then, including therein the single one 

 placed under Trichodictyon, and of which I have just endeavoured to 

 convey a very general conception, I believe I see five types. It is true 

 that Professor De Bary* alludes to but two, and also referring to those 

 two, and to the genus Penium (Breb.), while he conceives they are un- 

 doubtedly separated by distinct characters from each other, he thinks 

 those characters seem to be of so slight value as that these three types 

 may eventually have to be united in one genus.f But surely Penium 

 interruptum, or P. Digitus, or P. clostcrioides, ox P. Cylindrus, and others, 

 have little in common with Kiitzing's Palmoglosa-forms ; and, even ad- 

 mitting them all as belonging to the family Desmidiaceoe, if the generic 

 types alluded to should prove constant, which, so far as we know, I 

 should say they really seem to be, and as to which future research will 

 be useful to decide, it would seem more advisable to retain them as re- 

 presenting three distinct genera. 



I have said that Kiitzing's plants included in Palmoglcea seem to be 

 separable into five types, and I shall now, one by one, endeavour to point 

 them out : — 



( 1 .) Pahnoglcea Roemeriana (Kiitz.) seems altogether distinct from any 

 of the others. I have never seen it, but it seems to possess angulato- 

 globose cells, combined into a flattened frond-like expansion, growing in 

 water. "Whatever it be, it will, I think, be admitted that it has little 

 affinity indeed with any of the others, and that it should find no place 

 here. Kiitzing himself, indeed, places it under one of his subgroups, 

 under the subgeneric name of Limnodictyon. 



(2.) Palmoglcea monococca var. aruginea (Kiitz.) appears to me to be a 

 form referrible rather to Glceothece (Nag.)f than to this genus ; but in 

 Glceothece no conjugative or other generative process has been noticed, 

 and I shall not dare to enter into any disquisition as to whether the 

 forms included in that genus or their allies are or are not actually inde- 

 pendent organisms — that is to say, whether they themselves represent the 

 species, or are merely the transitory intermediate phases in the develop- 

 ment, or "alternations," so to speak, of higher plants. Be that as it may, 

 they are at least forms of more or less frequent recurrence to those who 

 seek for them ; and, under any circumstances, Glceothece appears to have 

 no immediate affinity with the remaining Palmoglcea forms; and I may, 

 besides, call to mind that the endochrome in Glceothece is " phy co- 

 chrome." It would, therefore, be superfluous and beyond the object of 

 this paper to enter into any description of them here. 



(3). Palmoglcea endospira (Kiitz.) = Cylindrocystis endospira (Breb.,) 

 and P. clostericlia (Kiitz.) = Endospira closteridia (Breb.), with their 

 distinctly well-marked parictally-wound spiral band of endochrome, 

 represent a type entirely distinct from the preceding or the following. 

 I conceive they really and naturally belong to the genus Spirotamia 



Op. cit., p. 30. f lb., p. 74. % " Gattungen einzelliger Algen," p. 57. 



