MICRASTEEIAS. 107 



Var. angulosa (Hantzscli) West & G. S. West, (PL L, 



figs. 3, 4.) 



Micrasterias angulosa Hantzscli in Eabenh. Alg. no. 1407, 1862; Nordst. 



Desm. Gronl. 1885, p. 10 ; Cooke, Brit. Desm. 1886, p. 62, t. 29 ; Nordst. 



Freshw. Alg. N. Zeal, and Austral. 1888, p. 29, 78 ; De Toni, Syll. Alg. 



1889, p. 1133 ; Eoy & Biss. Scott. Desm. 1893, p. 172, t. 4, f. 2. 

 Didymidium (Micrasterias) angulosum (Hantzscli) Eeinscli, Algenfl. 



Frank. 1867, p. 147, t. 8, f. 2. 



Helierella angulosa Kimtze, Eevis. gen. plant. 1891, p. 898. 

 Micrasterias denticulata Breb. var. angulosa (Hantzscli) W. & Gr. S. West, 



Alg. N. Ireland, 1902, p. 30. 



Cells more angular than in the type, often relatively 

 broader near the poles ; lateral lobes only divided by 

 primary and secondary incisions, the four subdivisions 

 being truncate with rounded ano'les. retuse, or retuse- 



o o 



emarginate. Cell- wall distinctly and densely punctate. 



Zygospore very similar to that of the type. 



Length 210-282 //,; breadth 184-230 /I; breadth of 

 isthmus 30-33 p. ; thickness 54 p. ; cliam. of zygospore 

 without spines 114-116 /x; length of spines 32 /x. 



ENGLAND. Westmoreland ! (Bissett). Lancashire ! 

 W. Yorks ! Warwick (Wills). Thursley Common, 

 Surrey ! Hants ! (Roy). Cornwall (Marquand). 



WALES.- -Capel Curig (Cooke $ Wills) and Rhyddu!, 

 C arnarvonshire . 



SCOTLAND.- -Sutherland !, Eoss !, Inverness, Aber- 

 deen, Kincardine, Forfar !, Perth !, Argyll ; zygo- 

 spores from Slewdrum, Aberdeen (Pot/ ^* Bissett}. 



IRELAND. Lough Akibbon, Donegal ! Near Ough- 

 terard, Galway ! Slieve Donard, Down ! Dublin, 

 Wicklow, and Westmeath (Archer). 



Geogr. Distribution. France. Germany. Galicia in 

 Austria. Norway. Sweden. Denmark. Bornholm. 

 Greenland. New Zealand. 



This variety lias been regarded by some authors as a species,, 

 but the distinctions between it and M. denticulata are too 

 slight and variable to warrant this separation. It only differs 

 from typical M. denticulata in the angularity of the lateral 

 lobes, which are not subdivided to so great an extent. The 

 ultimate divisions of these lobes are also more rounded, but 

 this feature is a very variable one. 



