72 BRITISH DESM1DIACEJL. 



93. Cosmarium truncatellum Perty. 

 (PI. LXXI, %s. 15, 16.) 



Eitastrum (Cosmarium) truncatellum Perty in Mittheil. d. naturforscli. 



G-es. in Bern, 1849, p. 173 ; Kleinst. Lebensf . 1852, p. 209, t. 16, f. 13. 

 Cosmarium truncatellum Perty ; Rabenh. Flor. Europ. Alg. Ill, 1868, 



p. 165; Arch, in Quart. Journ. Micr. Sci. 1873, p. 99 ; Joshua in Jouni. 



Bot. xx, 1882, p. 301; Racib. Norm. Desm. Poloii. 1885, p. 23 (sep.) ; 



Cooke, Brit. Desm. 1886, p. 91, t. 37, f . 9 ; De Toiii, Syll. Alg. 1889, 



p. 1017 ; West, Alg. N. Wales, 1890, p. 288 ; Alg. W. Ireland, 1892, 



p. 147 ; Roy & Biss. Scott. Desm. 1894, p. 177 ; Nordst. Index Desm. 



1896, p. 261 ; West & G. S. West, Alg. S. England, 1897, p. 486; Alga-fl. 



Yorks. 1900, p. 92. 

 Ursinella truncatella Kuntze, Revis. gen. plant. 1891, p. 926. 



Cells minute, about 1^ times broader than long, 

 deeply constricted, sinus open and acute-angled ; semi- 

 cells transversely oblong-hexagonal, lateral angles 

 bluntly conical, the short sides above the sinus con- 

 verging upwards into the broad flat truncate apex. 

 Side view of semicell subcircular. Vertical view 

 fusiform-elliptic, ratio of axes about 1:3. Cell- wall 

 smooth. 



Zygospore globose, furnished with numerous sharp 

 spines. 



Length 9*5-10'5/x; breadth 12'5-14'5 p. ; breadth of 

 isthmus 5'5 p. ; thickness 5 p.. 



ENGLAND. Risley Bog, Lancashire (Roy). Strensal] 

 Common, N. Yorks. (IF. B. Turner). Chobham 

 Common, Surrey ! 



WALES. Bethesda ! and Capel Curig ! (Cooke 

 Wills), Carnarvonshire. 



SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine, 

 Forfar. Zygospores from Aboyne, Aberdeen ; Dai- 

 brake, Kincardine ; Ninhaven, Forfar (Roy $ Bissetf). 

 Perth ! 



IRELAND.- -Moher Lough, Gal way ! Dublin and 

 Wicklow (Arcli-er). 



Geofjr. Distribution. Germany. Switzerland. Galicia 

 in Austria. Norway. Poland. United States. 



This species is characterized by the form of its semicells 

 and its open sinus. The narrowly fusiform vertical view is 

 also a noteworthy feature. The zygospores have been 



