PENIUM. 7-") 



\V.\i. i:s. Bog above the Capel Curio- lakes, and 

 Llyn Idwal, Carnarvonshire! 



Si OTF.AXD. Ross, Inverness!, Aberdeen, Kincardine, 

 Perth, Argyll, Arran (]{<>/ t y Jiiwtt). Sutherland ! 

 Ayr ! 



IRELAND. Sproule's Lough and near Lough Mag- 

 rath, Donegal ! 



d'rtxjr. Distribution. Russia. Ceylon. Singapore. 



This variety is probably far more widely distributed than 

 is here indicated, as it has undoubtedly been overlooked in 

 the past. 



2. Penium Navicula Breb. 

 (PI. VII, %s. 12-15, and 19.) 



Pot in in Naricula Breb. Liste Desm. 1856, p. 146, t. 2, f. 37; Arch, in 

 Pritcli. Infus. 1861, p. 751 ; Rabenh. Flor. Europ. Alg. 1868, III, p. 121 ; 

 Lund. Desm. Suec. 1871, p. 84, t. 5, f . 8 ; Kirchn. Alg. Schles. 1878, 

 p. 135 ; Wolle, Desm. U.S. 1884, p. 36, t. 5, f. 16 ; Cooke, Brit. Desm. 

 1886, p. 42, t. 16, f . 5 ; Mask. Further Notes N. Zeal. Desm. 1889, p. 2s, 

 t. 5, f. 51 a . ; West, Alg. W. Ireland, 1892, p. 127; Alg. Eng. Lak.- 

 Distr. 1892, p. 721 ; Roy & Biss. Scott. Desm. 1894, p. 252 ; West \- 

 O. S. West, Alg. S. England, 1897, p. 479 ; Alg. N. Ireland, 1902, p. 21 ; 

 Alg.-fl. Yorks. 1900, p. 45. 



Penium Sci-^inii Arch. Suppl. Cat. in Dubl. Univers. Zool. Bot. Assoc. 

 1S5\ p. 121, t. 11, f. 14, 15. 



Clot1<-,-'tniii Lens Jacobs, var. minor Jacobs. Desm. Danem. 1875, p. 168. 



Penimn dosterioides Ealfs, b. Navicula Klebs, Desm. Ostpreuss. 18"'.>, 

 p. 24, t. 3, f. 2. g. 



Cells small, 3-^5 times longer than their diameter, 

 unconstricted, fusiform, with the poles broadly 

 rounded ; cell-wall smooth and colourless ; each chloro- 

 plast with 5 or 6 longitudinal plates (or ridges) and 1 

 or 2 pyrenoids ; apical vacuoles often present with two 

 or three minute moving grannies. 



Zygospore subqnadrate, compressed, with rather 

 sharply produced angles to which the empty half-cells 

 are attached. 



Length 32-61 /t; breadth 10-15 ji; breadth of apices 

 6-7 /n ; length of zygospore 38-43 /u ; breadth of zygosp. 

 33-38 ,i. 



EXGLAXK Cumberland ! Westmoreland! (Bissett). 



