1919] Setchcll-Gardner : Myxopliyceae 13 



Meneghini, Conspeet. Alg. Eugan., 1837, p. 6 (in part), cenni 

 siilla organogr. e fisiol. delle Alg., 1838, p. 25 (sp. excL), Monogr. 

 Nost. Ital., 1842, p. 92 (emend.) ; Reichenbaeh, Nom, gen. pi. syst., 

 1841, p. 18; de Brebisson, Diet. univ. d'hist. nat., vol, 1, 1841, p. 417; 

 Endlicher, Gen. PI., suppl. Ill, 1843, p. 11; Kuetzing, Tab. Phyc, 

 vol. 1, 1846, p. 7 (as subgenus of Microcystis) , Sp. Alg., 1849a, p. 209. 

 Microcystis Kuetzing, Tab. Phyc, vol. 1, 1846, p. 7 (in part). Poly- 

 cystis Kuetzing, Tab. Phyc, vol. 1, 1846, p. 7 (as subgenus of Micro- 

 cystis), Sp. Alg., 1849flf, p. 210 (in part). 



In selecting the proper generic name for the group of species which 

 lias been for some years included under the name of Polycystis 

 Kuetzing and more recently still under the name of Microcystis Kuetz- 

 ing, it has seemed desirable to scrutinize closely the literature bearing 

 on the subject. Microcystis was proposed by Kuetzing in 1833 to 

 include ten species (1833a), now variously referred, but no one of 

 which remains in the more recent revisions of the genus. Further- 

 more the variety of algae, fungi, and gemmae included under the orig- 

 inal Microcystis precludes any preponderance of species of one genus 

 or general idea. The first species in the list, Microcystis Noltii Kuetz., 

 would now be referred to Euglena as the type specimen clearly 

 proves. In 1843 (p. 170), and again in 1845 (p. 148), Kuetzing 

 enumerated four species under his Microcystis, M. Noltii still being 

 included and placed first. No one of the four is unmistakably a 

 Microcystis in the sense of later authors, M. Noltii and M. olivacen 

 being species of Euglena, M. parasitica being doubtful but probably a 

 Microcystis of the later usage, while M. icthyohlahe, as used here, is 

 largely, at least, what is now called Clathrocystis aeruginosa (cf. also 

 Nordstedt, 1911, p. 264). In 1846 in the first volume of the Tahulae 

 Phycologicae (p. 7) Kuetzing separated his genus Microcystis into 

 three, retaining in Microcystis only M. olivacea, M. austriaca and M. 

 Noltii. These are all, seemingly at least, species of Euglena. In 1849, 

 in liis Species Algarum (pp. 208, 209) Kuetzing retained the same 

 species, adding to them M. minor, a very similar species. It seems, 

 therefore, that the final conception of Kuetzing points toward Euglena 

 rather than toward the species included by later writers. Most 

 writers, however, have employed Kuetzing 's genus Polycystis founded 

 in 1846. This is the second of the two segregates from Microcystis 

 and is fairly definite in its content. Kuetzing assigns it three species, 

 viz., P. elaheus, P. <ieruginosa and P. icthyoMahe. P. aeruginosa is 

 now separated as Clathrocystis aeruginosa, but the other two species 

 certainly seem cogeneric 



