MESOT7ENIUM. -V> 



7. Mesotaenium violascens De Bary. 

 (PL III, figs. 27-38.) 



lli'sotsenium violascens De Bary, Conj. 1858, p. 32, 74, t. 7, f. B ; Cooke, 

 lirit, Desm. LSS(), p. 47, t, 18,' f. 5 ; Nordst. Freshw. Alg. N. Zeal, isss, 

 ]. 72. 



1'iilinrnjlcea violascens Babenh. Krypt. Fl. Sachs. 1863, p. 107; Flor. 

 Europ. Alo-. iii, LSIJS, p. 117. 



Cells elliptico-cylindrical, 1^-2 times longer than 

 their diameter, gradually attenuated towards the 

 rounded apices; chloroplast an elliptical plate with 

 one pyrenoid ; cell-sap coloured violet. 



Zygospore obtusely angular. 



Length. 24-33 /i ; breadth 15-1 6'5 /*; diam. zygosp. 

 27-28 ju. 



EXCLAXD. Leicester (Roy). Devil's Jumps at Fren- 

 sham, Surrey! Enbridge Lake, Hants (/?"//). 



SCOTLAND. Inverness, Nairn, Aberdeen, Forfar (L'<>// 

 fy Bixsett}. Craig-an-Lochan, Perth ! 



IRELAND. Bray, Wicklow (Archer]. 



Geofjr. Distribution. France. Germany. Norway. 

 Sweden. Lapland in Russia. New Zealand. 



This plant is less cylindrical than most species of the genus, 

 mid its nearest ally is M. mirificiim Arch. It is, however, 

 scarcely so large as the latter species and not so elliptical in 

 outline. Nordstedt gives as the dimensions of his New 

 Zealand specimens: length 32-36 / t ; breadth 20-21 p. The 

 cell-sap is coloured violet owing to the presence of phyco- 

 porphyrin. 



B. Cells free-swimming. 



8. Mesotsenium purpureum West & Gr. S. West. 

 (PL III, figs. 25, 26.) 



Mfsotsenium purpureum West & G. S. West, Notes Alg. I, 1898, p. 2 

 (sep.) ; Alga-fl. Yorks. 1900, p. 42. 



Cells cylindrical and slightly curved, 3^-4^ times 

 longer than their diameter, apices rounded ; chloroplast 

 plate-like and rather thick ; cell-sap purple or violet in 

 colour. 



