I'KXICM. 7o 



Section A. 



1. Penium Libellula (Focke) Nordst. 

 (PL VII, figs. 6, 7.) 



Closterium Libellula Focke, Phys. Stud. 1847, p. 58, t. 3, f. 29. 



Penium dosterioides Ralfs, Brit. Desni. 1848, p. 152, t. 34, f. 4 : Arch, in 



Pritch. Iiifus. 1861, p. 751 ; Kabenh. Flor. Europ. Alg. Ill, isiis. p. 121 ; 



Kirchn. Alg. Schles. 1878, p. 135; Wolle, Desm. U.S. 1884, p. 35, t, 5, 



f. 18; Cooke, Brit. Uesm. 1886, p. 41, t. 16, f. 3 ; Nordst. Freslnv. Alg. 



N. Zeal. 1888, p. 71 ; West, Alg. W. Ireland, 1892, p. 127; Alg. En-. 



Lake Distr. 1892, p. 721 ; Borg. Ferskv. alg. Ostgronl. 1894, p. 9, t. 1, 



f. 1 ; Nordst. Index Desm. 1896, p. 75. 

 Closterium Lens Jacobs, (and var. intermedia Jacobs.) Desm. Danem. 1875, 



pp. 167 and 168. 

 Penium dosterioides Ealfs, a. typicum Klebs, Desm. Ostpreuss. 1879, p. 24, 



t. 2, f. 2/. 

 Penium Libellula (Focke) Nordst. Bornh. Desm. 1888, p. 184 ; Turn. 



Freshw. Alg. E. India, 1893, p. 20 ; West & G. S. West, Alg. S. England, 



1897, p. 479 ; Alg.-fl. Yorks. 1900, p. 45 ; Freshw. Alg. Ceylon, 1902, 



p. 135 ; Alg. N. Ireland, 1902, p. 21. 



Cells large, 5-7 times longer than their diameter, 

 imconstricted, fusiform, with rounded or more often 

 with subtruncate poles ; cell-wall smooth, often of a 

 yellowish-brown colour ; each chloroplast with about 

 8 longitudinal plates and 3-0 pyrenoids ; apical 

 vacuoles frequently present with several moving 

 granules. 



Zygospore globose and smooth. 



Length 230-356 /*; breadth oG-52 /u ; diam. x 



ENGLAND. Cumberland ! Westmoreland ! 

 W. and N. Yorks! Lancashire! Warwick (T !*///.< 

 Sussex (Haifa). Surrey! (Itulfa). Hants! (Ealfs). 

 Devon! Cornwall! (Haifa). 



WALES. Capel Curig ! (CWv A"- J |7Ky), Llyii Idwal ! , 

 Llyn-an-afon ! , near Dolbadarn Castle ! , Bettws-y-coed 

 (Hoy), Carnarvonshire! Llyn Coron, Anglesey! 



SCOTLAND. Sutherland ! Ross! , Inverness, Aberdeen, 

 Kincardine, Forfar, Perth!, Argyll (Hoi/ \ .IHwtf). 

 Ayr ! General in the Outer Heljrides ! 



IRELAND. Mayo ! Galway ! Kerry ! Dublin and 

 Wicklow (Archer). Donegal ! Down ! 



Geogr. Distribution. France. Germany. Italy. 



