SOJVIE KOETH AMERICAN DESMIDIE^. 255 



101. Staueastrttm connatum, Roy et Biss. in Journ. Bot. xxiv. (1886) p. 237. 

 {S. dejectum, Breb., var. connatum, Lund. Desni. Suec. p. 60, t. 3. lig. 28.) 



Var. AMERICANTJM, nov. var. (PL XVI. fig. 7.) Yar. semicellulis paulo loni^ioribus et 

 angustioribiis, spinis erectioribus longioribus, curvatis et validioribus. 



Long, sine spin. 24^, cum spin, 48 ^ot; lat. (s. spin.) 19-5^; lat. istlim. 6/x. 



S. hexacmithum, F. Gay (in Eev. Sc. Nat. ser. IIL iii. (1883) p. 303, t. 6. fig. 9), and 

 f. intermedia, B. Eiclil. & Gutw. (Nonn. Alg. Nov. 1894, p. 15, t. 5. fig. 54), seem to us 

 to be but forms of ^S*. connatum witli thicker spines. 



102. S. DiCKiEi, Balfs, Brit. Desm. p. 123, t. 14. fig. 23. 



Var. ciRCULARE, W. B. Turn. Treshw. Alg. of E. India, p. 105, t. 16. fig. 5. Forma 



majoi\ W. B. Turn. {I.e.). 

 Long 42-44 m; lat. 41-43^; lat. istlim. 9-5-10-5 /i. 

 Var. MAXIMUM, West & G. S. West, in Trans. Linn. Soc. ser. II., Bot. v. (1895) j) 72, 



pi. 8. fig. 19. (PI. XVIII. fig. 13.) 

 Long. 67-69^; lat. sine spin. 69-73^, cum spin. 82-86^; lat. isthra. 13-14*5^. 

 The American specimens of this variety were one and a half times as large as those 

 from Madagascar ! 



103. S. GLABHUM, Balis, Brit. Desm. p. 217 ; Boy, in Journ. Bot. xxviii. (1890) p. 337. 

 (Desmidium glabi'um, Ehrenb. ; Fhyeastrum glabrum, Kuetz. Phycolog. Germ. p. 137.) 



Var. (PI. XVI. fig. 8.) 



Long. 21 ^a; lat. s. spin. 25^, c. spin. 56^; long. spin. 17"5^; lat. isthm. 8/x. 



The spines were longer than in British specimens ; they were strongly infiexed and 

 straiglit in front view, but somewhat curved in vertical view. S. dejectum, Wolle (Desm. 

 U.S. pi. xl. fig. 7), is most probably a form of this species. 



104. S. coRNicuLATUM, Lund, Desm. Suec. p. 57, t. iii. fig. 23. 



Var. VAUIABILE, Nordst. Ereshw. Alg. of New Zeal. & Austr. p. 39, t. 4. fig. 17. 



Long. 29 ju, ; lat. 28'5 /x ; lat. isthm. 11*5 ^. 



The form seen had the angles distinctly but very slightly mucronate. 



105. S. SIBIRICUM, Borge, in Bilumg Sv. Vet.-Akad. Handl. xvii. (1891) Afd. iii. no. 2, 

 p. 9, t. 1. fig. 4. 



Var. occiDENTALE, nov. var. (PL XVI. fig. 9.) Var. semicellulis apicibus levissime 

 concavis, prof undius constrictis ; a vertice visis triangularibus, lateril)us valde con- 

 cavis, angulis obtusis (non porrectis). 

 Long. 12-5-17-5 ^ ; lat. 19-30 /x ; lat. isthm. 5-7 /x. 

 Sab. Orono, Maine. 



This appears to be most nearly related to S. sibi'ricum in its front view, though having 

 a deeper constriction; it is also closely akin to -S'. minutissimmn, lleinsch (Algenfl. 

 Franken, p. 153, t. 13. fig. 1 ; Contrib. Alg. et Fung. t. 16. fig. 3), var. constrictum, West 

 (iu Journ. Linn. Soc. (Bot.) xxix. (1892) p. 173, pi. 24. fig. 11), but differs in its angles 

 being less rounded and in the more concave sides of the vertical view. 



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