148 BRITISH DESMIDIACE^E. 



IRELAND. Dublin and Wicklow (Archer). 

 Geogr. Distribution. Germany (forma). Norway. 

 Sweden. Bornholm. 



G-utwinski lias described a Desmid from Galicia which he 

 named C. pseudofontigenum (vide Griitw. ' Walir. d. Prioritat/ 

 1890, p. 67; f Flor. Glon. Okolic Lwowa/ 1891, p. 40, t, i, 

 f. 11), but we do not see how it can be specifically separated 

 from C. fontigenum Nordst. as it only differs in the reduction 

 of the small central protuberance. In dimensions and in all 

 other characters it agrees well with C. fontigenum and there- 

 fore it can only be considered as a form of it. 



12. Cosmarium undulatum Corda. 

 (PI. LIX, figs. 1-3, 5.) 



Cosmarium undulatum Corda in Aim. cle Carlsbad, ] 839, p. 243, t. 5, f . 26 ; 



Ralfs, Brit. Desni. 1848, p. 97, t. 15, f. 8 ; Arch, in Pritch. Infus. 1861, 



p. 732, t. 2, f. 33, 34 ; Eabenh. Flor. Europ. Alg. Ill, 1868, p. 165 ; 



Lund. Desm. Siiec. 1871, p. 35 ; Kirchn. Alg. Scliles. 1878, p. 149 ; 



Wolle, Desm. U. S. 1884, p. 67, t. 16, f. 20, 21 ; Cooke, Brit. Desni. 1886, 



p. 97, t. 37, f . 16 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 196 ; West, 



Alg. N. Wales, 1890, p. 289 ; Alg. W. Ireland, 1892, p. 151 ; Alg. Eng. 



Lake Distr. 1892, p. 726; Eoy & Biss. Scott. Desm. 1894, p. 177; 



Nordst. Index Desm. 1896, p. 265 ; West & G. S. West, Alg. S. England, 



1897, p. 488 ; Alga-fl. Yorks. 1900, p. 73. 

 Diclymidium (Cosmarium) undulatum Reinsch, Algenfl. Frank. 1867, 



p. 117 (in part). 



Euastrum (Cosmarium) undulatum Gay, Monogr. loc. Conj. 1884, p. 60. 

 Ursinella undulata Knntze, Eevis. gen. plant. 1891, p. 925. 



Cells rather small, quadrate-elliptic, about 1-^-1-J 

 times as long as broad, deeply constricted, sinus narrow 

 with a dilated extremity ; semicells widening upwards 

 near the base, then subsemicircular, margins with 10 

 to 12 equal undulations. Side view of semicell sub- 

 circular. Vertical view elliptic, ratio of axes 1 : I'oo. 

 Cell-wall smooth. Chloroplasts axile, each with one 

 pyrenoid. 



Zygospore unknown. 



Length 54-64 ^ ; breadth 39-52 p ; breadth of isth- 

 mus 12-5-17 /x: thickness 27'5-30 //,. 



ENGLAND.- -Westmoreland ! (Ralfs). W., N., and E. 

 Yorks! Cheshire (Eoy). Warwick (Wills). Glou- 

 cester (Ralfs). Surrey! Sussex (Ralfs). Cornwall! 

 (Marquand). 



