OF THE DESMIDIE^. 



'23 



Genus DIDYMOPRIUM (Kg.). — Filament gelatinous, cylindrical, regu- 

 larly twisted; joints ^\dth a bidentate process or angle at each side ; end view 

 circular, or broadly elliptic, with two opposite projections formed by the 

 ansrles : endochrome radiate. 



Dn)yiioPRiUMG^/-ei-///iV(Kg.). — Sheath 

 distinct; joints broader than long, ivith 

 a thickened border at their junction ; angles 

 bidentate ; teeth angular ; transverse view 

 broadly elliptic. Sporangium orbicular, 

 formed within one of the two conju- 

 gating joints, the endochrome passing 

 over from one by a narrow connecting 

 tube produced between the otherwise 

 but little altered broken-up single joints. 

 L. 1-464"; B. 1-^70". =I)esmidium cy- 

 lindricmn (auct.), Arthrodesmus ? cyl. 

 (Ehr.), Desmidium comjiressuni (Corda), 

 D. Grevillii (De B.). G.B., I., R, G., 

 Prussia, U.S.A. 



D. Borreri (Ralfs). — Joints inflated, 

 barrel-shaped, longer than broad, icithout 

 a thickened border at their junction ; angles 

 bicrenate, crenatures rounded ; transverse 

 vieiv circidar. Sporangium elliptic, fomied 

 within the (for some time) persistent 

 extensions from the conjugating joints, 

 which do not previously break up into 

 single joints, but couple, still united in 

 the filament, in a confused or zigzag 

 manner, some of the joints remaining 

 unchanged, (ii. 38, 39.) L. 1-939" ; 

 B. 1-1030". = Bambusina Brebissonii 

 (Kg., Breb.). G.B., L, F., G., U.S.A. 



Genus APTOGONUM (Ralfs). — Filament S-4-angular ; joints not con- 

 stiicted, plane or crenated at the lateral margins, united only at the outer 

 portions of each of their end margins by mutual projections, thus producing 

 intervening central oval foramina. 



mina broadly oval j in e. v. triangular. 



Aptoggntjm Baileyi (Ralfs). — Joints 

 in f V. quadrangular, about as broad as 

 long, their lateral margins plane] fora- 



angles somewhat roimded. (in. 5, e.v. 6.) 



U.S.A. 



Genus DESMIDIUM (Ag.). — Filament 3-4-angular or compressed, regu- 

 larly twisted ; joints bidentate or bicrenate at the angles or lateral margins, 

 and either closely imited throughout the whole of their end margins by a 

 thickened border, or only at the outer portion of each by mutual projections, 

 and thus producing intervening central oval foramina. 



DESMinior aptogonum (Breb.). — , G.B., I., F., G., Italy, Sweden, U.S.A. 

 Joints in f. v. quadrangular, broader [ D. quadrangulatiim (Ralfs). — Filament 

 than long, with two rounded crenatures quadrangular, varying in breadth from 

 on each lateral margin, imited at the its twisting, having two longitudinal 

 outer portion only of each end margin \ waved lines; joints in f v. broader than 

 by mutual projections, thus producing \ long, with two someivhat rounded cre- 

 intervening central oval faramina. G.B., ! natures on each lateral margin, imited by 



F., G., U.S.A. a. Filament triangular, 

 regularly tudsted, crenatures roimded. 

 L. 1-1490"; B. 1-1000". (ni.7, e.v. 8.) 

 i3, filament compressed, crenatures shal- 

 lower, and slightly angular. L. 1-1295"; B. 

 1-925" . = Aptogomwi Desmidium (Ralfs). 

 D. Swartzii (Ag.). — Filament trian- 

 gular, equal, vtdth a single longitudinal 

 waved dark line formed bv the third 



the whole of their end margins ; e. 

 quadrangular ; endochrome fom--raved. 

 (II. 37, 40.) L. 1-1244"; B. 1-603" to 

 1-455". = Z>. quadranqulare (Ko;.), G.B., 

 F.,G., U.S.A. 



D. undulatum (Corda). — Filament tri- 

 angular-, joints in f v. with a slight 

 central notch at each side, and/o?/7- broad 



angle; joints in fi-ont view somewhat by the whole of their end margins, 

 quadi-angiilar, broader than long, with | D. didymum (Corda). — Filament tri- 

 two slightly angular crenatmes on each ! angular; joints in f v. bidentate, broader 

 lateral margin, imited at the whole of than long, imited by the whole of their 

 their end margins by a thickened border ; I end margins ; e. v. triangidar ; angles 

 end -view triangular ; endochrome three- I acutely hi/id. = Desmidiuin biiidum 

 rayed. L. 1-2000" to 1-1666"; B. 1-633". | (Menegh.). G., Italy. 



Genus SPH.^ROZOSMA (Corda). — Filament compressed; joints deeply 

 divided on each side, thus forming two segments, and giving a pinnatifid 



:^ A 2 



