I'KXITM. l ( 'l 



which there are five or six longitudinal ridges on each chloro- 

 phist. The normal number of ridges is four,, and it is fnun 

 this character as seen in the vertical view that the specific 

 name is derived. 



'27. Penium inconspicuum West. 

 (PI. X, figs. 1-5-17.) 



Penium inconsi>icuuin West, New Brit. Freshw. Alg. 1894, p. 4, t. 1, 

 f. 6, 7 ; Nordst. Index Desm. 1S96, p. 144 ; West & G. S. West, Some N. 

 Amer. Desm. 1896, p. 237 ; Alg. S. England, 1897, p. 479 ; Alga-fl. 

 Yorks. 1900, p. 48; Liitkem. Desm. Millstiittersees, 1900, p. 6 (sep.) ; 

 West & G. S. West, Alg. N. Ireland, 1902, p. 22 ; Freshw. Alg. Ceylon, 

 1902, p. 135. 



Cells very minute, about 3 times longer than their 

 diameter, subcylindrical, slightly and gradually (but 

 distinctly) constricted in the middle, gradually nar- 

 rowed towards the apices, which are subtruncate ; 

 cell-wall smooth and colourless. 



Zygospore unknown. 



Length 15-19 /z ; breadth 4'8-5'8^. 



EXGLAXD. Elter Water, Westmoreland ! Pilmoor, 

 N. Yorks! Riccall Common, E. Yorks! Keston 

 Common, Kent ! Puttenham Common, Surrey ! 



V 



WALES. Cap el Curig, Carnarvonshire ! 



SCOTLAND. Near Callernish and near Balallan, 

 Lewis, Outer Hebrides ! 



ICELAND. Lough Gartan, Donegal ! 



Geoyr. Distribution. Austria. Ceylon. Siam. United 

 States. 



This is one of the smallest and most characteristic species 

 of the genus, but owing to its size it is readily overlooked. 



28. Penium minutum (Ralfs) Cleve. 

 (PI. X, figs. 1,2.) 



Docidium minutum Ealfs, Brit. Desm. 184S, p. 158, t. 26, f. 5 ; Eeinsch, 

 Algenfl. Franken, 1867, p. 183 ; Jacobs. Desm. Danem. 1*75. p. 162, t. 7, 

 f. 9 ; Wolle, Desm. U. S. 1SS4, p. 52, t, 1O, f. 9; t. 50, f. 29-31 : Cooke, 

 Brit. Desm. 1886, p. 16, t. 8, f. 1 ; Key A: Biss. Scott, Desm. Isil4, p. 49 

 (sep.i. 



Penium Ralfsii De Bary, Conj. 1858, p. 45, 73, t. 5, f. S; E?y Biss. 

 Scott. Desm. 1894, p. 253. 



