EUASTRUM. 25 



near the base and also towards the apex, with a 

 scrobiculatioii showing at the middle of the margin 

 on each side ; basal angles of semicell quadrate. 

 Vertical view elliptic, with two protuberances on each 

 side, and a third smaller one showing between and 

 beneath them ; also with the scrobiculation between the 

 central protuberances on each side. Cell-wall very 

 finely punctate. 



Zygospore unknown. 



Length 50-02 //, ; breadth 30-40 ^ ; breadth of isth- 

 mus 7'5-13/x; thickness 20-23*5^. 



ENGLAND. Loughrigg, Westmoreland (Bennett). 

 Thursley Common, Surrey ! Dartmoor, Devon ! 



SCOTLAND. Sutherland ! , Eoss ! , Inverness ! , Aber- 

 deen ! , Kincardine, Forfar, Perth ! , Argyll, Arran 

 (Pi oij Bis sett). Often abundant in the Outer Hebrides ! 



IRELAND. Loughs Cloffher and Machuffh. and near 



~ o o ' 



Glenties, Donegal ! Ballynahinch, Loughs Athry, 

 Aunierin, and Derryclare, Gralway ! Glengariff, Adrigole, 

 and Castletown, Kerry ! 



Geoor. Distribution. Germany. Austria and Galicia. 



v 



Italy. Norway. Sweden. Denmark. Poland. S. Russia. 

 Faeroes. United States. 



E. inerme is a rare species in England and Wales, but often 

 occurs in great abundance in the west of Scotland, the Outer 

 Hebrides, and the west of Ireland. In these situations it is 

 frequently associated with large numbers of E. ventricosum. 



It is a species of definite and constant shape, with very 

 characteristic markings, and it cannot well be mistaken for 

 any other British species of the genus. Ealfs was greatly in 

 error in associating it with Euastrum elegans, a species with 

 which it has no close affinity. 



i/ 



13. Euastrum cuneatum Jenner. 

 (PL XXXVI, fig. 9.) 



Euastrum cuneatum Jenner in Ealfs' Brit. Desrn. 1848, p. 90, t. 32, f . 3 a ; 

 Arch, in Pritch. Infus. 1861, p. 931 ; Rabenh. Flor. Europ. Algar. Ill, 

 1868, p. 187 (formae a et 6) ; Xordst. Norses Desm. 1873, p. 9 ; Cooke. 

 Brit. Desm. 1886, p. 76, t. 34, f. 6 : Wolle, Freshw. Alg. U.S. 1887, p. 3") 

 t. 58, f. 12, 13 ; West, Alg. W. Ireland, 1892, p. 137 ; Alg. Eng. Lake 

 Distr. 1892, p. 723; Roy & Biss. Scott. Desm. 1893, p.' 176; Nordst. 



