COSMA1UUM. 43 



We have only observed this minute species on one occasion. 

 Its outward form and granulation are very characteristic. 



247. Cosmarium cylindricum Ralfs. 

 (PL XCIV, fig. 7.) 



Cosmarium cylindririim Ralfs in Ann. Mag. Nat. Hist, xiv, 1844, p. 392, 

 t. 11, f. 1 ; Hass. Brit. Freshw. Alg. 1845, p. 365, t. 86, f. 4 ; Ealfs, Brit. 

 Desm. 1848, p. 10(5, t. 17, f. 4; Arch, in Pi-itch. Infus. 1861, p. 734, t. 3, 

 f. 16-17 ; Rabenh. Flor. Europ. Alg. III. 1868, p. 176; Wille, Norges 

 Ferskv. Alg. 1880, p. 36 ; Cooke, Brit. Desm. 1887, p. 122, t. 43, f. 1-4 ; 

 West, Alg. W. Ireland, 1892, p. 157 ; Alg. Engl. Lake District, 1892, p. 

 728 ; Nordst. Index Desm. 1896, p. 95 ; Borge, Beitriige Alg. Schweden, 

 1906, p. 29. 



Penium Ralfsii Kiitz. Spec. Alg. 1849, p. 167 ; Delp. Desni. subalp. 1877, 

 p. 90, t. 15, f. 26-28. 



Dysphinctium ? cylindricum Eeinsch, Algenfl. Franken, 1867, p. 181 ; 

 Turn. Freshw. Alg. E. India, 1893, p. 44. 



Galocylindrus Ralfsii Kirchn. Alg. Schles. 1878, p. 142. 



Calocylindrus cylindricus (Ralfs) Racib. in Spraw. Kom. fizyjogr. Akad. 

 Um Krakow. 1884, p. 9 [= a. typica Racib.] ; Cooke, Brit. Desm. 1887, 

 p. 122, t, 43, f. 1-4; West, Alg. N. Wales, 1890, p. 291. 



Disphinctium Ralfsii Hansg. in Osterr. bot. Zeitschr. XXXVII, 1887, p. 

 99 ; Prodr. Algenfl. Bohm. 1888, p. 186 ; De Toni, Syll. Alg. 1889, p. 888. 



Cells rather small, subcylindrical, a little more than 

 twice as long as broad, very slightly constricted ; 

 semicells snbrectangular or subqnadrate, with the 

 sides slightly divergent, apical angles rounded, apex 

 convex-truncate. Cell-wall furnished with small 

 granules rather densely arranged in somewhat in- 

 definite longitudinal series, 25-27 visible round the 

 margin of a semicell. Vertical view circular. 

 Chloroplasts . . . . ? 



Zygospore unknown. 



Length 38-57 /x; breadth 19-24/x; breadth of 

 isthmus 15-17 p.. 



ENGLAND. - Helvellyn, Westmoreland ! Sussex 

 (Rnlfs). Kent (Rolfs). Cornwall (Rolfs). 



WALES.- -Llyn Padarn !, and Capel Curig ! (Ooolce 

 Wills), Carnarvonshire. Machynlleth, Montgomery 

 (Rolfs). 



SCOTLAND.- -Aberdeen, Kincardine, Forfar, Perth, 

 Arran (Roy $ Bissett). 



IRELAND.- -Athry Lough, Galway ! Dublin and 

 Wicklow (Arch or) . 



