Conjugatc-e, Desmidiaceae, Artlirodesmus. 1057 



Desra. p. 134, Hansg. Prodr. p. 202, WoUe Brit. Desm. p. 95.— Cel- 

 lula) ut iu Cosniario medio profuude coustrictcu et iu duas semicel- 

 lulas a^quimagnas distiacta); seraicellula? singuUe iitroque latero spi- 

 nis singulis vel geminatis, subulatis, firmis instructa), e vertice visa^ 

 oblonga) vel fusiforrai-elliptica^, sine inflatione raediana; chlorophora 

 axilia, laminaria; zygota levia vel aculeata. 



Scclio 1. Tetracanthium (Naeg.) Hansg. : cellulas 4 (semicellulse ideoque 2) acu- 

 leis simplicibus iustructa^. 



1. Arthrodesmus Incus (Breb.) Hassall Freshw. Alg. p. 357, n. 2, t. 85, 2544 

 f. 10, Ralfs Brit. Desmid. p. 118, n. 2, t. XX, f. 4, Archer in 

 Fritch. Inf. p. 737, t. III, f. 36, Rabenh. Alg. n. 1204, 1224 et 

 1570,Rabenh. FI. Eur. Algar. III, p. 226, Kirchn. Alg. Schles. 

 p. 156. Cooke Brit. Desni. p. 135, t. 47, f. 4, Hansg. Prodr. p. 202, 

 n. 419, WoIIe Desm. U. S. p. 97, t. 24, f. 1-10, Cosmariu?n Incus 

 Breb. in Menegh. Syn. in Linn. 1840, p. 228 n. 17 (sub Staura- 

 siro), Euastrum retusum Kuetz. Phyc. germ. p. 130. — Parvus,tam 

 longus quam latus, levis, constrictione lineari obtusa vel late ex- 

 cisa ; seraicellulis oblongo-quadrangularibus, angulis externis acu- 

 leatis, internis rotundatis inermibus, aculeis longis singulis diver- 

 gentibus ; zygotis orbicularibus, aculeatis, sine aculeis 22 (j.. diam. 

 Hab. in aquis iraprirais turfosis totius Europoe, iraprirais in Gal- 

 lia, Belgio, Germania, Hungaria, Fennia, Bohemia, Anglia, Scotia, 

 Suecia, Norvegia, Dania, Italia, Araerica boreali, Sibiria, Groen- 

 landia; in ins. Cuba (Lagerhelm), in Birmania anglica Asia) (Josiiua). 

 — Diara. raax. 10-36 a, constr. lat. ad 6-9 a. Adest etiam forma 

 seraicellulis basi gibbosis, aculeis rectis vel convergentibus. — 

 Var. divergens Archer in Pritch. Infus. p. 737, Cooke 1. c. p. 

 136: seraicellulis saapius seraiorbicularibus, nodulo distincto conne- 

 xis, aculeis divergentibus. In stagnis Britanni.-e. — Var. convergens 

 Arch. 1. c. p. 737, t. 3, f. 36, Cooke 1. c; semicellulis ad basim 

 globosis; aculeis parallelis vel convergentibus. Cum prascedente. — 

 Var. intermedius Wittr. Anteckn. Skand, Desraid. fig. 6: parvus, 

 tam longus quara latus vel paullulum longior; incisura in raedio 

 cellulx' parva, obtusangula; seraicellulis breviter cuneatis, angulis 

 aculeatis, aculeis longis, singulis divergentibus. Dira. cell. (sin. acul.) 

 12-15 i; 11-13; long. acul. 7-8 ij..; lat. isthm. 8-9 [/.; crass. cell. 

 7-8 a. In Scandinavia et Bohemia. — Var. americanus Turner in 



67 



