CLOSTKR1UM. M 



xjr. Distribution. France. Germany. Austria and 

 Galicia. Portugal. Poland. Bornholm. Siam. Central 

 Africa (var.). United States. Brazil. Patagonia. 



This is OIK- of the rarest species of tlie genus,, and one of 

 the most elongate. It is characterised by the recurved apices 

 and its smooth cell- wall. 



Forma brevior West. (PI. XXI, figs. 3-5.) 



Cl. praelongum forma Nordst. Frcshw. Alg. N. Zeal. 1888, p. 08, t. 3, 

 f. 22-24. 



Cl. i-n>l<>n<nu forma brevior West, Add. Alg. W. Yorks. II, 18!)1, p. 244; 

 West & G. S. West, New and Int. Freshw. Alg. 1890, p. 151 ; Nordst. 

 Index Desm. 189(3, p. 205; West & G. S. West, Alg. S. England, 1897, 

 p. 480; G. S. West, Alga-fl. Canibr. 1899, p. Ill; West & G. S. West, 

 Alga-fl. Yorks. 1900, p. 54 ; Alg. N. Ireland, 1902, p. 22. 



Cells shorter, 14-22 times longer than the diameter. 



Zygospore globose and smooth. 



Length 198-320 /x; breadth 12-5-17 /A; diam. 

 zygosp. 40-46 [JL. 



ENGLAND. W. and N. Yorks ! Cambridge ! Essex ! 

 Middlesex (zygosp. from Ruislip Reservoir) ! Surrey ! 



SCOTLAND. Bressay, Shetlands ! 



IRELAND. Ram's Island and entrance of River 

 Ballanderry, Lough Neagh ! 



Geogr. Distribution. - - Portugal. Sweden. New 

 Zealand. 



This short form is more frequently met with than typical 

 Cl. wxlonfjum. 



42. Closterium strigosum Breb. 

 (PI. XXI, figs. 6, 7.) 



Closterium strigosum Breb. Liste Desm. 1850, p. 153, t. 2, f. 43 ; Arch, in 

 Pritch. Infus. 1801, p. 747; Kabcnli. Flor. Em-op. Algar. Ill, ISlis, 

 p. 130; Kirchn. Alg. Schles. 1878, p. 139; Wolle, Desm. U.S. ]ss|, 

 p. 42, t. 0, f. 13, 14, t. 53, f. 9, 10; De Toiii, Syll. Alg. 1889, p. M".) . 

 West, Alg. Eng. Lake Distr. 1S92, p. 720 ; Koy & Biss. Scott. Desm. 

 1894, p. 249 ; Nordst. Index Desm. 1890, p. 241. ' 



Cl. strigosum a. typicum Klebs, Desm. Ostprenss, 1879, p. 8. 



Arthrodia strigosa Kuntze, Eevis. gen. plant. 1891, p. 884. 



Cells of moderate size, 16-20 times longer than 

 their diameter, slightly curved, median portion of 

 cell straight, towards the extremities incurved, 



