STAURASTKUM. 89 



Brit. Desm. 1887, p. 167, t, 58, f. 1 ; De Toni, Syll. Alg. 1889, p. 1202 ; 

 Anders. Sverig. Chlor. 1890, p. 11 ; West & G. 8. West, New and Int. 

 Freshw. Alg. 1896, p. 159, t. 4, f. 53-56 ; Some X. Amer. Desm. 1896, 

 p. 262, t. 16,. f. 32 ; Alg. S. England, 1897, p. 494 ; G. 8. West, Variation 

 Desm. 1899, p. 391, t. 11, f. 5-15 ; West & G. 8. West, Alg. X. Ireland, 

 1902, p. 49 ; Alga-fl. Yorks. 1902, p. 103 ; Him, Desm. Finnland, 1903, 

 p. 20 ; G. 8. West, Brit. Freshw. Alg. 1904, p. 172, f. 65, F. 



Phycastrum Ralfsii Kiitz. Spec. Alg. 1849, p. 181. 



PJi. brachiiitum Perty, Kleinst. Lebensf. 1852, p. 210, t. 10, f. 33. 



Cells small, about as long (including processes) as 

 broad, deeply constricted, sinus acute and rectangular, 

 minutely excavated at the apex ; semicells somewhat 

 triangular, apex and sides nearly straight, angles pro- 

 duced to form stout divergent processes of variable 

 length, which are 2-3-fid at the apex. Vertical view 

 3-5-angular, sides strongly concave, sometimes with a 

 very slight median inflation ; processes hollow to the 

 extreme tip. 



Zygospore irregular and variable in outline, some- 

 times quadrangular, with a few blunt processes. 



Length 27-36'o^; breadth 25-48 fi; breadth of 

 isthmus 5-9 \L ; diam. zygosp., without processes, 

 21-30 u. 



ENGLAND.- -Westmoreland, and in the plankton of 

 Easedale Tarn! W., N., and E. Yorks! Gloucester 

 (Ealfs). Surrey (zygospores from Thursley Common) ! 

 Devon (Hurris) ! Cornwall (Ealfs). 



WALES. Capel Curig (Cooke & Wills) !. Moel Siabod, 

 Llyn Idwal, near Conway, and Llyn Teyrn. Snowdon, 

 Carnarvonshire ! Dolgelly, Merioneth (Ealfs). 



SCOTLAND.- -Eoss !, Inverness!, Aberdeen, Kincar- 

 dine, Forfar. Perth !, Argyle, Arran ; zygospores from 

 Curran and Clochnaben, Kincardine (Roy & Biss.). 

 Sutherland ! Somewhat rare in the plankton ! Lewis, 

 Outer Hebrides, and in the plankton ! Shetlands, and 

 in the plankton of the Orkneys and Shetlands ! 



IRELAND. Mayo ! Donegal ! Galway, and in the 

 plankton ! Kerry, and in the plankton ! Dublin and 

 Wicklow (Arch.). Down ! 



Geogr. Distribution. France. Belgium. Germany. 

 Switzerland. Galicia in Austria. Hungary. Italy. 



