COSMAKIUM. 25 



Length 42-52 ^ ; breadth 32-45 /x ; breadth of 

 isthmus 12-16 /x ; thickness 21-30 p. 



ENGLAND.- -Crummock Water, Cumberland ! Lough- 

 rigg, Westmoreland ! Bisley Bog, Lancashire ! Cnlling- 

 Avortli, Wigton Moor, Baildon, Ad el Bog, and Moughton 

 Fell, W. Yorks ! Pilmoor, Mickle and Great Shnnnor 

 Fells, X. Yorks! Riccall Common, E. Yorks! Glou- 

 cester (Haifa'). Xear Chapel Wood, Surrey ! Sussex! 

 Hants (Bennett). Cornwall (Marquand). 



WALES.- -Bethesda !, Capel Curig !, Snowdon!, and 

 Glyder Fawr (Roy), Carnarvonshire. Dolgelly, Meri- 

 oneth ! 



SCOTLAND.- -Xear Brin, Inverness ; near Alford, 

 Aberdeen; Strachan, Kincardine (Roy $ Bissett). 



IRELAND.- -Xear Westport, Mayo! Xear Recess, 

 Gahvay ! 



Geogr. Distribution.- -France. Germany. Galicia in 

 Austria. Italy. Norway. Sweden. Denmark. S. 

 Russia. United States. Brazil. 



C. Broumei differs from all allied species in the possession 

 of a large protuberance in the middle of each semicell. The 

 granulation is also characteristic, being very line., and com- 

 parable to that of C. bin-tit in. It is a rare Desmid and we 

 have only met with it as solitary examples. 



The zygospore of this species is as yet unknown, ns that 

 figured by Ralfs ('Brit. Desm.' 1848, t. 33, f. 7) is most 

 probably that of C. Pseudobroomei . It is not unlikely, how- 

 ever, that the zygospore of C. Broomei will be found to be 

 smooth. 



The Cosmarium figured by Wolle ('Desm. U. S.' 1884, 

 t. 17, f. 8, 9) as a " smaller variety and zygospore "of C. 

 llroomei is now known as another species C. spinosporum 

 Lagerh. 



236. Cosmarium biretum Breb. 



(PI. CI, figs. 1-8.) 



Cosmarium biretum Breb. in Ralfs' Brit. Desm. 18-48, p. 102, t. 16, f . 5 ; 

 Arch, in Pritch. Infus. 1861, p. 733 ; Rabenh. Flor. Europ. Algar. Ill, 

 1868, p. 171; Lund. Desm. Suec. 1871, p. 30; Nordst. Desm. Arctose, 

 1875, p. 26 ; Desm. Ital. 1876, p. 40 ; Kirchn. Alg. Schles. 1878, p. 154 ; 

 Wolle, Desm. U. S. 1884, p. 86, t. 17, f. 1, 2 [figures bad] ; Cooke, Brit. 

 Desm. 1887, p. 108, t, 39, f. 5 [figures bad" ; Hansg. Prodi-. Algenfl. 

 Bohm. 1888, p. 202, 251 ; Hoff in Nordst, Bornh. Desm. 1888, p. 195 ; 



