STAURASTEUM. 1 87 



37. Staurastrum dispar Breb. 



Staumstrum dispar Breb. Liste Desm. 1856, p. 144, t. 1, f. 27; Nordst. 



Freshw. Alg. N. Zeal. 1888, p. 41 ; Roy & Biss. Scott. Desm. 1893, p. 237. 

 Phycastrum dispar (Breb.) Grogn. Plant, cryptogam. -cellul. du departm. 



de Saone-et-Loire, Autun, 1863, p. 262. 



Cells small, about as long as broad, very deeply 

 constricted, sinus open and acute-angled ; semicells 

 narrowly elliptic-rhomboid or elliptic fusiform, dorsal 

 margin somewhat more convex than the ventral margin, 

 lateral angles acutely rounded. Vertical view triangular, 

 angles subacute, those of one semicell alternating with 

 those of the other, sides convex. Cell-wall finely 

 granulate, granules arranged in concentric rings around 

 the angles. 



Zygospore ? 



Length 27'5 p.; breadth 27-28^. 



ENGLAND. Delamere, Cheshire (Roy). Leicester 

 (Roy). Enbridge Lake, Hants (Roy). 



WALES. Capel Curig, Carnarvonshire (Roy). 



SCOTLAND. Sutherland, Ross, Aberdeen (zygospores 

 from Slewdrum), Kincardine, Forfar, Perth, Dumbarton 

 (Roy Bissett}. 



Geoar. Distribution. France. Norway. Sweden. 



' t/ 



New Zealand. 



This species is recorded by Roy from several English 

 counties and one Welsh one, also by Roy and Bissett from 

 several Scottish counties; they also report the zygospores 

 from Slewdrum in Aberdeen, but give neither description nor 

 figure of them. We have not seen anything exactly corre- 

 sponding to Brebisson/s original figure, but the following Irish 

 form should most probably be referred to St. dispar: 



Forma. (PI. CXXVII, fig. 7.) Angles of semicells truncate- 

 emarginate; vertical view with slightly concave sides. Length 

 24fjL ; breadth 23-24 M ; breadth of isthmus 6^. Cf. W. & (f. S. 

 West, 'Alg. N. Ireland/ 1902, p. 52, t. 2, f. 30. 



IRELAND. Lough Gartan, Donegal. 



38. Staurastrum pilosellum sp. not:. 

 (PI. CXXVIII, figs. 7, 8.) 



Cells small, about 1J times as long as broad, deeply 

 constricted, sinus open and rectangular; semicells 



