KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 22. N:0 8. 25 



it appears that the inner part of the sinus between the semicells of this species is in a 

 living plant somewhat widened. 



Gen. 2. Desmidium A g. 



1. D. Swartzii Ag. Syst. Alg. p. 9; Diatoma Swartzii Ag. Disp. Alg. Suec. IV, p. 34; 



in Sv. Bot, tom. 7 (1812) tab. 491, fig. 1—3. 



Forma Ralfsii Rab. Flor. Eur. Alg. 3, p. 154. 



Lat. 36 — 50 /u; long. 18 — 20 /u; lat, zygospor. 23 — 28 ,u; long. z. 36 u. 

 Blueskinbay (34); Hutt Valley (59); Papakauri (109); Taupo (154, 156 cum zygosp.); 

 Omatangi (240). 



2. D. (Didymoprium) coaretatum Nordst. nov. spec. Tab. 2, fig. 3. 



D. a Desmidio gracilicipiti (Nordst.) Lagerh. differt cellulis apicem versus magis 

 attenuatis. Latitudo apicis tertia pars diametri transversalis cellula?. Membrana subtilis- 

 sime punctata- punctis longitudinaliter ordinatis. 



Long. 25 — 34 ,«; lat. bas. 34 — 38 "; lat, isthm. 33 [*; lat, apic. 12 — 14 /u; crass. 

 24—26 fi. 



Taupo (157). 



Since the zygospores of D. quadratum cc have been discovered (Lagerh. Bidr. 

 Am. Desm. p. 227, tab. 27, fig. 1), I agree with Lagerheim in considering the var. (i 

 graciliceps as a distinct species. The fig. 2 in Lagerh. 1. c. (forma major!) appears to 

 be magnified 300, and not 400 diameters. (Long. cell. 42 — 45 {*; lat, max. 45 ft; lat. 

 apic. 21 /u- lat, isthm. 35 — 36 /u). Desmidium quadratum in Josh. Burm. Desm. tab. 22, 

 fig. 3 seems also to belong to D. graciliceps as a forma intermedia (long. 24 — 26 ,u; lat. 

 30 /"; lat. isthm. 21 ,«; lat. apic. 15 ,u; crass. 24 ju). — Desmidium quadratum in Wolle 

 Desm. Unit. St. p. 26, tab. 49, fig. 5 is more deeply constricted in the middle of the 

 cells than the common form, and I therefore consider it as a var. constrictum mihi. Lepto- 

 zosma catenula Turn. Som. Desm. pag. 934, tab. 16, fig. 2 looks as a Didymoprium 

 {graciliceps or an allied form) vieved from the side. 



3. I). Baileyi (Ralfs) De Bar. Conjug. p. 76; Nordst. Alg. et Charac. 1, p. 4; Apto- 



gonum Baileyi Ralfs Brit, Desm. pag. 208. 



[i undulatuin (Mask.) Aptog. undul. Mask. N. Z. Desm. p. 302, tab. 11, fig. 1 — 3. 



Lat, 27 /u; long. 18 ,«; lat. apic. et isthm. 25 ,«. 



Papakauri (109); Omatangi (240). 



The genus Aptogonum was founded by Ralfs 1. c. upon one species, but he already 

 in the Appendix to the same work pag. 208 added another, that of D. Baileyi, whereby 

 the characters of the genus given pag. 63, became altered. Relegating Aptogonum Des- 

 midium into Desmidium, Mr. Archer (in Pritch,- Infus. p. 723) considered Desmidium 



K. Sv. Vet. Akad. Handl. Bd. 22. N:o 8. 



