Micrasterias] xi. desmidiace^ (West). 347 



Var. subpinnatifida W. et G. S. West in Journ. Bot. 1897, 

 p. 86, t. 366, f. 7. 



HuiLLA. — In paludibus exsiccandis ; April 1860. No. 176. Inter 

 Utriculuriiim ciimJiantham, Morro de Lopollo ; April 1860. No. 179. 



This variety appears to connect M. arcuata with M. pimmtifida ; its 

 lobes are thicker and more horizontal than in typical examples of the 

 former, and the basal ones much resemble those of the latter. The 

 lobes, however, are not so thick and have not the same form as those 

 of M. jnnnatijida, the apex of the polar lobe is retuse in the middle, 

 and the lobes all possess that small terminal sharp spine characteristic 

 of all specimens of M. arcuata. 



2. M. tropica Nordst. in Vidensk. Medd. Naturh. Foren. Kjiiben. 

 1869, no. 14-15, 219, t. ii. f. 15 (1870). 



M. er-pansa var. y : Wallich in Ann. Mag. Nat. Hist. ser. 3, 

 V. 276-7, t. xiii. f. 9 (1860). 



Forma. Apical processes almost horizontal, also with two large 

 granules, one on each side of the extremity of each sinus ; W. et 

 G. S. West in Journ. Bot. 1897, p. 86, t. 366, f. 1. 



HuiLLA. — In paludibus exsiccandis ; April 1860. No 176. 



This form has the four larger granules (or papillije) pos-sessed by 

 var. (lu'uuipnse Racib. [in Flora (1895), Ixxxi. 34, t. iii. f. 15], but has 

 not the teeth at their apex. 



Var. elegans W. et G. S. West, I.e., t. 366, f. 2. 

 PuNGO Andongo. — In stagnis prope Anbilla (Condo> ; March 1857. 

 No. 177. 



Var. crassum W. et G. S. West in Journ. Bot. 1897, p. 87, 

 t. 366, f. 3. 



Huir.LA. — Inter Utricular iam cymlxmtham, M-orro de Lopollo ; April 

 1860. No. 179. 



3. M. robusta W. et G. S. West in Journ. Bot. 1897, p. 87, 

 t. 366, f. 5, 6. 



HuiLLA. — In paludibus exsiccandis ; April 1860. No. 176. 



This beautiful and characteristic species has a very robust appear- 

 ance on account, of the shortness and thickness of the lobes ; the 

 subuncinate form of the lateral lobes is also peculiar. 



4. M. poloniea W. et G. S. West in Journ. Bot. xxxiii. 66 

 (1895) ; xxxv. p. 87 (1897). 



M. Kitchelii '^ oWe. forma poloniea B. Eichl. & Gutw. in Rospr. 

 Akadem. Umiejet. Krakow. Wydz. matem.-prz. ser. ii, torn. viii. 

 vol. xxviii. 173, t. v. f. 41 (1895). 



Huir.LA.— In editis de Morro de Lopollo ; Feb. 1860. No. 192. 



The African form has a higher polar lobe than the Polish one, and 

 the infra-apical incision is a little more open. Eichler & Gutwinski's 

 measurement igiven in the text, "long. cell. = 86 ^," is evidently a 

 mistake, as their figure measures but 39 /i. 



5. M. crenata Breb. in Ealfs, Brit. Desm. 75, t. vii. f. 2 and 

 t. X. f. 4 (1848) ; W. et G. S. West in Journ. Bot. 1897, p. 87. 

 This plant is proportionately longer than M. truncata Breb. ; 

 it has a more robust and deeper polar lobe, which is never retuse 



