STAURA STRUM. 55 



? St. Xotari.sii Delp. Spec. Desm. subalp. 1877, p. 157, t. 13, f. 1-2. 



? St. bullosum Benn. Freshw. Alg. Engl. Lake Distr. 1886, p. 11, t, 2, f. 18-20; 



Cooke, Brit, Freshw. Alg. 1887, p. 152, t, 51, f . 5 ; De Toni, Syll. Alg. 



1889, p. 1170. 



Cells of rather more than medium size, about 1 J times 

 longer than broad, deeply constricted, sinus acute, 

 opening widely ; semicells broadly oval, angles very 

 obtusely rounded ; cell- wall closely covered with 

 numerous short acute spines, evenly distributed except 

 that they are wanting in the centre of the apex of the 

 semicell. Vertical view 3- (rarely 4- or 5-) angular, sides 

 very slightly convex, angles bluntly rounded. Cell-wall 

 minutely punctate. 



Zygospore unknown. 



Length, without spines, 77-79 u ; with spines, 85- 

 86 (JL ; breadth, without spines, 58-65 \L ; with spines, 

 72-74 \L ; breadth of isthmus, 21-22 \L ; length of spines 

 3-8 fi. 



ENGLAND.- -Loughrigg, Westmoreland (Bennett). Den- 

 holme, Cam Fell and near Brickden, W. Yorks ! New 

 Forest, Hants ! Dartmoor, Devonshire (Harris). 



SCOTLAND.- -Xear Mill of Maidencraig, Haughton, 

 Tillyfour, below Aboyne, Dinnet, Koynach Moor in 

 Cromar, Castleton, Braemar, Aberdeen ; near Durris 

 Bridge, Cainmie, Dalbrake, Slack of Birnie, Kincardine ; 

 Lundie Bog, Easter Ogil in Fern, Forfar (Roy & Biss.). 

 Plankton of Loch Trebister, Shetlands ! 



Geogr. Distribution- -France. Germany. Galicia and 

 Austria. Italy. Norway. Sweden. Bornholm. Nova 

 Zembla. Spitsbergen. Greenland. United States. 

 Brazil. 



St. Saxonicum is distinguished from St. polytrichum by the 

 form of its semicells, which are relatively longer and more 

 broadly oval, and its shorter spines are also more numerous. 



81. Staurastrum cumbricum West. 

 (PL CXXXVII, figs. 13, 14.) 



St. cumbricum West, Alg. X. Wales. 1890, p. 16, t. 5 f. 5, t. 6, f. 30. 



Cells rather large, li times longer than broad, deeply 



