172 BRITISH DESMIDIACE^l. 



47. Closterium Pritchardianum Arch. 

 (PL XXII, figs. G-14.) 



Closterium Pritchardianum Arch. Descript. new Cosm., etc. 1862, p. 250, 

 t. 12, f. 25-27 ; Eabenh. Flor. Europ. Algar. Ill, 1808, p. 129 ; Cooke, 

 Brit. Desm. 1886, p. 22, t. 10, f. 1, t. 15, f. 7 ; Do Toni, Syll. Alg. 1889, 

 p. 830 ; Roy & Biss. Scott. Desm. 1894, p. 247 ; Nordst. Index Desm. 

 1896, p. 206 ; West & G. S. West, Alg. S. England, 1897, p. 480 ; G. S. 

 West, Alga-fl. Cambr. 1899, p. Ill ; West & G. S. West, Alga-fl. Yorks. 

 1900, p. 56; Alg. N. Ireland, 1902, p. 22. 



Cl. pronum Breb. forma C. Pritchardianum Eeinsch, Algcnfl. Frank. 1867, 

 p. 188. 



Arthrodia Pritchardianum Kuntze, Revis. gen. plant. 1891, p. 884. 



Closicrium turgidum Ehreiib. var. dccoratum West, Alg. Eng. Lake Distr. 

 1892, p. 720. 



Cells large, very slightly curved, 12-17 times longer 

 than their diameter, outer margin about 24 of arc, 

 inner margin straight or very slightly concave, not 

 tumid, gradually attenuated towards the apices, which 

 are slightly recurved, narrow, and truncate ; cell-wall 

 finely striated, 35-40 striae visible across the cell, striae 

 composed of fine punctae, of a yellowish colour, fre- 

 quently becoming reddish-brown ; chloroplasts with 

 six to eight ridges, and a central series of 7 or 8 

 pyrenoids ; terminal vacuoles with many moving 

 granules. 



Zygospore globose, subglobose, or ovoid, smooth. 



Length 350-590 //, ; breadth 80-4(3 /x ; breadth of 

 apices 7-8 ^ ; cliam. zygosp. 83-108 p. 



ENGLAND. Near Bowness, Westmoreland ! Crims- 

 worth Dean, W. Yorks ! Market Weighton, E. Yorks ! 

 Sheep's Green, Cambridge ! Sutton Park, Warwick 

 (Wills). Mill-pond, E. of Chapel Wood, S.E. Surrey ! 

 Tremethick Moor, Cornwall (with zygosp.) ! 



SCOTLAND. Ross, Aberdeen, Kincardine, Forfar, 

 Perth, Stirling (Roij cj- Itiwtt). Inverness ! Orkneys f 



IRELAND. Gweedore and Lough Akibbon, Donegal ! 

 Howth, Dublin (Air her). 



dcntjr. Distribution. France. Germany. Austria 

 and Galicia. Italy. Norway. Sweden. N. Russia. 

 China. Brazil. Argentina. 



The cell-wall of CL Pritchardianum is of a yellowisli-brown 



