I'LOSTKKII M. 1 71 



f. 15; Cooke, Brit, Dosni. ISM;, p. i'i, t, 9, t. :>, ; Hansg. Proclr. Alt-vull. 

 Bohiii. isss, p . isu: (*,. Tom, Svll. Alg. L889, p. 827 ; West, Alg. Eng. 

 Lake Distr ism', p. 7i'(; K,..y &Biss. So .11. !),.sni. isiti. ],. i'i 1 .) ; Nordst 

 Imlux Dcsrn. ISiHi, p. L'SM ; \\Yst \ <i. S. West, Alg. S. Kn-land, 1S!)7, 

 p. IMt; Al-a-fl. York.s. UHHJ, p. 5ii ; A1-. N. Ireland., 1902, p! 1'2. 

 Arthrui.Ha tunjida Kuutzo, iievis. gun. plant. 18U1, p. 8.S4. 



Cells large, moderately curved, 11-12 times lon^t-p 

 llian their diameter, outer margin about -jO of arc, 

 inner margin not tumid, gradually attenuated towards 

 the extremities, which are distinctly recurved, apices 

 subtruncate; cell- wall finely striated, from oO-35 

 stria? visible across the cell, yellowish-brown or reddish- 

 brown in colour ; chloroplasts with about eight ridges 

 and a central series of 7 or 8 pyrenoids ; terminal 

 vacuoles with many moving granules. 



Zygospore unknown. 



Length 650-791 /A; breadth 58-7-5 /x; breadth of 

 apices 12-15/x. 



ENGLAND. Cumberland ! Westmoreland ! Lanca- 

 shire ! N. Yorks! Cheshire (It a //*). Essex! Surrey! 

 ( K.'lfs). Sussex (Raffs). Kent ! (Rolfs)'. Hants ! (Ralfs). 

 Cornwall ! (Ralf*). 



WALES. Capel Curig ! (Cuofo- $ inV/.v), Cllyder 

 Fawr (Roy), and Snowdon ! , Carnarvonshire. Dolgelly, 

 Merioneth ! Lynn Coron, Anglesey ! 



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

 deen, Kincardine, Forfar, Perth, Dumbarton, Argyll, 

 Bute, Fife (Hoy $ Bissdt). 



IRELAND. Near Glenties, Donegal ! Loughs Aunierin 

 and Creggan, Gal way ! Near Sugar-loaf Mt., Castle- 

 town, and Adrigole, Kerry ! Dublin and Wicklow 

 (Archer). 



Gcof/i: Distribution. France. Germany. Austria 

 and Galicia. Hungary. Italy. Norway. Sweden. 

 Bornholm. S. Russia. Poland. Siberia. Japan (var.). 

 W. Africa. United States. W. Indies. Brazil. Ecuador. 

 Paraguay. 



This is one of the largest and most characteristic species 

 of the genus. It is by no means common. Cl. Inn/ i<hun 

 Elirenh. subs]), (/iijuiifi'inn Nordst., a native of Brazil, is the 

 largest known Desmidj reaching 1 a length of over l,oUU /j. 



