SOME IVOimi AMERICAN DESMIDIE^. 251 



^ranulis 8 utrobique instructis, apicibus subrectis et glabris, intra angulos basales 

 graiiulis parvis 2-8, infra apices et intra anijulos suporiores medinm tonus cum 

 granulis magnis in seriebus vertiealibus et obliquis (circiter i obliquis), cum dopros- 

 sionibus triangularibus 6 circa granulum unumquemque; a vertice visjje elliptico- 

 oblongse, polis subtruncatis granulis parvis paucis instructis, lateribus granulis 

 magnis (circ. 10) instructis, intra polos et latera granulis ordinatis, in ccntro glabrae ; 

 a latere visse subcirculares, apicibus pa^ne glabris, lateribus granulis magnis 5 ornatis. 

 Long. 51-57 n ; lat. 44-18-5 m; lat. isthm. 120-15^1 ; lat. apic. 22^; crass. 33 ft. 

 This has a very similar outline to C. confimim, Cooke, *amhiguum, West, in Journ. 

 Linn. Soc. (Bot.) xxix. (1892) p. 156, pi. 21. tig. 13, but ditFers altogether in its 

 ornamentation, which also distinguishes it from C. trachypleurum, Lund., and its 

 varieties, as well as from C. subtholiforme, Racib., var. 3Ia linvernianum, Racib. in 

 Pamiet. Akad. Krak. xvii. (1890) p. 91, t. 1. fig. 40. 



86. CosMARiUM AMCENUM, Breb. in Ralfs, Brit. Desm. p. 102, t. xvii. fig. 3. 



Var. COMPACTUM, nov. var. (PI. XV. fig. 13.) Vin\ cellulis niulto brevioribus et 



latioribus, granulis in seriebus 8 vertiealibus ordinatis. 

 Long. 40 /u; lat. 27 /t; lat. isthm. 13'5 n ; crass. 17 a*- 



'87. C. ORDINATUM, nobis. (PI. XV. fig. 14.) [C. hrasilieme, Nordst., *ordiimtum, 

 BoBrg. in Vidensk. Meddel. 1890 (1891) p. 40, t. 4. fig. 32. 

 Long. 22 (Jt^ ; lat. 19"5 [jb ; lat. isthm. 6-5 (Ij. 



88. C. BoECKii, Wille, Norges Ferskv. Alg. p. 28. t. 1. fig. 10. 



Porma. (PI. XV. fig. 7.) 



Long. 32-5-33 (Jt,; lat. 29 5-325 ^; lat. isthm. 8-8'5 ^ ; crass. 18 /a. 



This is a common American form of this species, and differs somewhat from Wihe's in 

 the arrangement of its central granules. Wolle's figure has too many granules aloni§ 

 the mars^ins and is otherwise inaccurate. 



89. C. TAXiCHONDKUM, Lund. Desm. Suec. p. 39, t. 2. fig. 13. 



Var. ANGTJLATUM, nov. var. (PL XV. fig. 8.) Var. cellulis late hexagonis, semicelluMs 

 lateribus subrectis sed leviter undulatis, granulis tribus intra apices truncatos et 

 granule singulo juxta isthmum ; a vertice visis polis emarginatis ; membrana minute 

 scrobiculato-punctata. 



Long. 25 (Jtj ; lat. 31 fjt, ; lat. isthm. 6*5 (ju ; crass. 13'5 [/j. 



The following is a list of the many varieties of this and other aUied species :— 



Cosmarium taxichondrum, Lund., var. subundulatum, Boldt. 



j^ ^, ,, „ f. subdenticulatum, West. 



„ „ ,, var. emarginatmn, West. 



„ „ „ var. compressum, W^est. 



„ „ „ var. dentatuni, West. 



„ „ ,, var. bidentulum, Lagerh. 



,, „ „ var. lithuanicum, Racib. 



,, „ „ var. nudum, W. B. Turn. 



