STAURASTRUM. 13 



47. Staurastrum O'Mearii Arch. 

 (PL CXXXII, figs. 5-8.) 



Staurastrum O'Mearii Arch. Suppl. Cat. Desm. 1858, p. 254, t. 21, f. 8-13 ; 

 in Pritch. Infus. 1861, p. 738 ; Rabenh. Flor. Europ. Alg. 1868, p. 204 ; 

 Nordst. Xorges Desm. 1873, p. 27 ; Arch, in Journ. Bot. 1874, p. 93 ; 

 Gay, Monogr. loc. Conj. 1884, p. 66 ; Cooke, Brit. Desm. 1887, p. 142, 

 t. 50, f. 1 ; De Toni, Syll. Alg. 1889, p. 1143; Liitkem. Desm. Attersees, 

 1893, p. 563 ; Roy & Biss. Scott. Desm. 1894, p. 23 ; West & G. S. West, 

 Alg. S. Engl. 1897, p. 493 ; Comere, Desm. de France, 1901, p. 163, t. 11, 

 f. 22 ; West & G. S. West, Alg. N. Ireland, 1902, p. 44 ; Georgev. Desm. 

 Wlasina-See, 1909, p. 203 ; Borge, Botan. Notis. 1913, p. 28. 



St. Pseudincus Reinsch, Spec. Gen. Alg. 1867, p. 15, t. 5, c.II, f. 1-5 (ex 

 parte = = f. 2-gona). 



Arthrodesmus Incus v. iiitfnnedius Wittr. Skandinav. Desm. 1869, p. 15, 

 t. 1, f. 6 (f. 2-gona) ; Jacobs. Desm. Danem. 1875, p. 205, t. 8, f. 26, 

 b & c. 



Cells very small, about as long as broad, constriction 

 not very deep, sinus rectangular, somewhat acute at 

 its apex ; semicells triangular, apex broad and truncate, 

 lateral margins very slightly convex, upper angles sub- 

 acute and each furnished with a fairly stout diverging 

 spine. Vertical view 2-4- (usually 3-) angled, sides very 

 slightly convex, angles with a stout spine. 



Zygospore spherical, with numerous long and delicate 

 spines. 



Length, without spines, 12-17[x; breadth, without 

 spines, 10-18*5 ^ ; breadth of isthmus 5-8 (JL ; length of 

 spines 5-1 k u. ; diam. zygosp., without spines, 12-14pu 



ENGLAND.- -Borrowdale, Cumberland ! Near Bow- 

 ness (Biss.), Helvellyn, Scandale and Stickle Tarn, West- 

 moreland ! Cocket Moss, near Griggleswick, and bog 

 2 miles south of Clapham, W. Yorks ! Puttenham and 

 Thursley Commons, Surrey ! Enbridge Lake, Hants 

 (Roy}. Dartmoor, Devonshire (Harris). Halgavor 

 Moor, Cornwall ! 



WALES. Capel Curig, Snowdon, and Glyder Fach 

 (at 2,200 ft.), Carnarvonshire ! Ffestiniog, Merioneth ! 



SCOTLAND. Sutherland, Aberdeen, Kincardine, For- 

 far, Perth, Argyle and Arran (Roy & Biss.). Orkneys ! 



IRELAND. - -Donegal ! Galway ! Kerry! Dublin and 

 Wicklow (Arch.). Down ! 



