174 BRITISH DESMIDIACE.l']. 



Zygospore unknown. 



Length 313-423 /x,; breadth 57-9 /*. 



ENGLAND. W., K, and E. Yorks ! Cambridge ! 

 Kssex! Surrey! Hants! (7/o//)- Cornwall I (Mar quand). 



WALES. G-iyder Facli (at' 2,200ft,), Carnarvonshire! 



SCOTLAND. Loch Hempriggs, Caithness; nearTnin, 

 Ross, Scotston Moor, Aberdeen (Uoij $ 7//x.sv//). Glen 

 Slice, Perth ! Rhiconich, Sutherland ! Near Tarbert, 

 Harris, Outer Hebrides ! 



Ii.'MLAND. Near Gweedore, River above Crolley 

 Bridge, and Lough Anna, Donegal ! Near Westport, 

 Mayo ! Near Leenane, Oughterard, Clifden, and 

 Ballynahinch, Galway ! Dublin and Wicklow (ylvr// />). 



Gent/r. Distribution. France. Germany. Austria 

 and Galicia. Sweden. Denmark. N. Russia. Green- 

 land. Japan. Java (form). Australia. Central and 

 E. Africa. United States. Guiana. Patagonia. 



r~> 



The Closterium pronum o recent authors does not strictly 

 agree with the Clo*t<'rinm described by Brebisson under I hat 

 name. Brebisson described the cell-wall as being yellowish 

 or pale-brown and very delicately striated, but these striations 

 have not since been detected. We have never yet seen a 

 specimen in which there was the slightest trace of striation 

 or even colouration of the cell-wall. The breadth given by 

 Brehisson (12-10 ju) is also much greater than the breadth 

 of any specimen we have seen. 



It is not an uncommon species in large bodies of water, 

 such as at the margins of lakes, etc., and it is also a con- 

 stituent of the fresh-water plankton. 



The terminal vacuoles are very long, and the moving 

 granules can wander along for some distance. 



49. Closterium aciculare Tuffen West. 

 (PI. XXVT, figs. 18, 19.) 



Closterium aciculare Tuffen West, Eem. Diat. Desm. I860, p. 15:1, t. 7, 

 f. 16; Arch, in Quart. Journ. Micr. Sci. 1866, p. 181- Cooke *Brit! 

 Desm. 1886, p. 36, t. 15, f. 1 ; Do Toni, Syll. Alsy. 1889, p. 837; Koy & 

 Biss. Scott. Desm. 1894, p. 243 ; Norclst. Index Desm. 1896, p. 38. 



Arthrinl!,!. urii-nlitris Kuiitze, Eevis. gen. plant. 1891, p. 883. 



Cl. grar'ih' llrrli. forma <tr,i,:Ulima West, Ala:. W- Ireland, 1892, p. 122 

 t. 19, f. 15, 



