1920] Setchell-Gardncr: Chlorophyccae 187 



one-third or more. It varies in the length-breadth proportions of the 

 segments, and plants with longer segments have been named forma 

 longiarticidaturn by Collins (Phyc. Bor.-Amer. (Exsicc.), no. 1735). 



n. Hormiscia Fries 



Filaments simple, attached at the base by rhizoids developing from 

 a few of the basal segments, either intramatrical, extramatrieal or 

 both ; segments multinucleate, all above the few basal ones similar and 

 capable of division and producing zoospores or gametes; chromato- 

 phore covering the segment wall, entire or more or less coarsely reticu- 

 late, with few to many pyrenoids ; multiplication by akinetes formed 

 by l)reaking up of the filaments into individual segments with thick 

 walls, either producing new filaments or zoospores; reproduction by 

 macrozoospores, by microzoospores and by gametes, produced manj^ 

 in a segment; macrozoospores obovoid, extending posteriorly into a 

 long "tail," provided anteriorly with 4 cilia; microzoospores smaller 

 with less obvious tail and 4 cilia ; sexual reproduction by 2-ciliated 

 (possibly in some species by 4-ciliated) iso- or hetero-gametes. 



Fries, Flora Scanica, 1835, p. 327. Urospora Areschoug, Observ. 

 Phyc, 1866. 



The genus Hormiscia, as constituted by Fries, comprised two 

 :-pecies, viz., H. penicilliformis and H. Wormskiolclii. The identity 

 of the second species is clear enough, but that of the first rests some- 

 what in doubt. It seems likely, however, that the Conferva pe^iicilU- 

 formis Roth is, in part at least, made up of the species more recently 

 assigned under that name as well as under that of Urospora mirahilis 

 Aresch. In such case, it seems best to follow Hazen (1902, pp. 146, 

 147) and adopt the name Hormiscia Fries rather than Urospora 

 Aresch. 



The genus Hormiscia, as at present understood, includes about 

 fifteen described species inhabiting the cooler waters of tlie Northern 

 Hemisphere. The filaments are characteristically simple but occasion- 

 ally may be branched. The branches are the result of injuries or, 

 at least, of some disturbance of the normal course of development. 

 In our own experience they are rare. Usually the branches are short 

 and rhizoidal, sometimes occurring in pairs, but at times they are 

 longer, with evidence in both cases of some disturbance of normal 

 growth at the point of origin. 



