BRITISH DESMIDTACIvK. 



Forma perundulata nol. (PI. XXVII, fig. 11.) 



dilatatum Lund, i'ormn, West, Alg. W. Ireland, 1S92, p. Us, 

 t. 19, f. 6. 



Cells rather more elongate; semicells with 10-1-1 

 undulations along each lateral margin. 



Length 200-262 /x; breadth (maximum) 12-5-14 p.; 

 breadth of apices 11-12 p.. 



IRELAND. Oroinaglonn, Kerry ! 



. Distribution. United States. 



Var. dilatatum (Oleve) nob. (PI. XXVII, fig. 12.) 



Pleurotseniuni ililiituhrni Clcve, Sverig. Dcsm. 1804, p. 404, t. 4, f. (i. 

 Doci.dium dllcdalum Lund. vn.r. siilinnliilntuiti West, AU;\ W. Ireland. 

 1S92, p. 118, t. 19, f. 7. 



Cells relatively a little shorter ; semicells less deeply 

 undulated, generally slightly tumid about the middle, 

 and with a slight constriction above the basal undula- 

 tion ; cell-wall often strongly punctate. 



Length 187-205 /A; breadth at base of semicells 

 15'5-1G /u, ; breadth at middle of semicells 10-17 /x ; 

 breadth of apices 1:3-14 /u. 



SCOTLAND. Rhiconich, Sutherland ! 



IKK LAND. Near Ougliterard, Galway ! Glen Caragli, 

 Kerry ! 



Geor/r. Distribution. Sweden. Lapland in Russia. 



The apices of this variety are as dilated and truncate ;is 

 those of the type, but the marginal undulations are much 

 less pronounced, and the semicells arc slightly tumid. 



o. Docidium nobile (Richt.) Lund. 

 (PI. XXVII, figs. 13-15.) 



ricin-nl:i'iihnii nnliili' Jliclitor in Hcdwigia, 18G5, p. 129, f. l-,3 ; Eabenh. 

 Kl..r. Europ. Al-'ur. Ill, LS(i,s. p. ]42. 



i iKiliili- (1,'idit.) Lund. Desm. Succ. 1871, p. SS ; Aivh. in Mk-r. 

 .Tourn. xii, is7l', p. S(i ; Cooler, I!rit, Dcsm. 1SM5, p. ];{, t. 7, f. !5 ; De 

 ii, Syll. Al--. 1889, p. 873 ; Eoy & Uiss. Scott, Desm. ]S!)|., p. 241. 



Cells small, elongated, 10-12 times longer than 

 their diameter; semicells very gradually tapering from 

 base to apex, base distinctly plicated, lateral margins 

 with about S undulations; apices not conspicuously 



