COSMARIUM. 199 



thicker cell-wall, and its more pronounced scrobiculations. 

 Owing to the thickness of the cell-wall the latter have the 

 appearance of short canals, and their large size and the 

 comparative closeness of their disposition give the exterior of 

 the cell-wall a slightly rough appearance. 



48. Cosmarium pyramidatum Breb. 

 (PL LXIV, figs. 5-7.) 



Cosmarium pyramidatum Breb. in Ralfs' Brit. Desni. 18-18, p. 94-, t. 15, 

 f . 4 a-c ; Arch, in Pritch. Iiif us. 1861, p. 731, t. 3, f. 1-4, 15 (in part) ; 

 Rabenh. Flor. Europ. Alg. Ill, 1868, p. 162; Lund. Desm. Suec. 1871, 

 p. 41 ; Delp. Desm. Subalp. 1877, p. 33, t. 9, f. 30-33 ; Kirchn. Alg. 

 Schles. 1878, p. 149 ; Wolle, Desm. U. S. 1884, p. 69, t. 14, f. 16 ; Cooke, 

 Brit. Desm. 1886, p. 86, t. 36, f. 13; Hansg. Prodr. Algenfl. Bolim. 



1888, p. 197 ; De Toni, Syll. Alg. 1889, p. 969 ; West, Alg. N. Yorks, 



1889, p. 292 ; Alg. N. Wales, 1890, p. 288 ; Heimerl, Desm. alp. 1891, 

 p. 596 ; West, Alg. W. Ireland, 1892, p. 144 ; Alg. Eiig. Lake District, 

 1892, p. 724 ; Eoy & Biss. Scott. Desm. 1894, p. 173 ; Nordst. Index 

 Desm. 1896, p. 215 ; West & G. S. West, Welw. Afric. Freshw. Alg. 

 1897, p. 115 ; Alg. S. England, 1897, p. 485 ; Alga-fl. Yorks. 1900, p. 78 ; 

 Alg. N. Ireland, 1902, p. 33. 



Didymidium (Cosmarium) pyramidatum Reinsch, Algenfl. Frank, 1867, 



p. 107. 

 Cosmarium pyramidatum b. typicum Klebs, Desm. Ostpreuss. 1879, 13. 31, 



t. 3, f. 18, 19, 31. 

 Ursinella pyramidata Kuntze, Revis. gen. plant. 1891, p. 925. 



Cells large, about 1^ times as long as broad, truncate- 

 elliptic in outline, deeply constricted, sinus very narrow 

 and dilated towards the apex ; semicells truncate- 

 pyramidate, basal angles well rounded, sides convex 

 and in the upper part converging, upper angles obtuse, 

 apex narrowly truncate. Side view of semicell elliptic 

 oblong. Vertical view elliptic, ratio of axes about 

 ] : 1'7. Cell- wall minutely scrobiculate. Chloroplasts 

 axile, each with two pyrenoids. 



(Zygospore globose and tuberculated.) 



Length 58-100 /* ; breadth 45-62 p. ; breadth of 

 isthmus 17'5-20//,; thickness 26*5-36 /x. 



ENGLAND.- -Cumberland ! Westmoreland! (Ralfs). 

 AY., N., and E. Yorks ! Lancashire ! (Ralfs). Cheshire 

 (Rolfs). Warwick (Wills). Surrey I (Ralfs). Sussex 

 (Ralfs). Kent (Rolfs). Hants! (Bennett). Devon! 

 (Bennett). Cornwall! (Ralfs). 



