STAURASTRUM. 179 



Alg. 1889, p. 1170; ? Heimerl, Desm. alpin. 1891, p. 605 ; Roy & Biss. 

 Scott. Desm. 1893, p. 241 ; Lagerh. Chlor. Abessin. IT. Kordofan, 1893, 

 p. 1(53 ; Schmidle, Lappmark Siisswasseralgen, 1898, p. 54 ; Gutw. Flor. 

 Alg. Mont. Tatr. 1909, p. 471. 



Cells small, a little broader than long, deeply con- 

 stricted, sinus slightly open, narrowly acute-angled ; 

 semicells oblong-elliptic, with a rather flattened apex. 

 Vertical view triangular, sides very slightly concave, 

 angles rounded. Cell- wall granulate, granules some- 

 what irregularly scattered and a little more prominent 

 at the ano-les. 



o 



Zygospore unknown. 



Length 33 ^ ; breadth 36 JJL ; breadth of isthmus 13 /x. 



SCOTLAND.- -Near Stratbpeffer, Ross; Cairnmonearn, 

 Kincardine (Roy $ Bissett). 



Geogr. Distribution- -France. Germany. Sweden. 

 Galicia in Austria. Madagascar (forma ?) . Abyssinia . 



We regard this species as exceedingly doubtful. The 

 figure in Ralfs' ' British Desmids/ of which we give a copy, 

 is very poor, and the original description is much too brief. 

 Gutwinski, Heimerl, Roy, Lagerheim, and Schmidle are the 

 only authors who have recorded it since its description in 

 1848, and HeimerPs measurements (length 38-49 /LI ; breadth 

 37-44 /n) are considerably larger than those obtained by 

 measuring Ralfs' original figure. Wolle's supposed figures 

 of th,'-. Desmid (< Desm. IT. S. ; 1884, t. 41, f. 41, 42) are too 

 uncertain to be of any value. 



It is possible that St. rugulosum is merely a form of St. 

 alternans, but the available evidence is insufficient to make 

 a definite statement regarding its exact position. 



We have ourselves recorded what we believed to be a form 

 of St.rugnlosum from Madagascar (cf. W. & G. S. West, 'Alg. 

 Madag. ; 1895, p. 74), but we are not at all certain of the 

 correct position of this form. 



36. Staurastrum punctulatum Breb. 

 (PL CXXVII, figs. 8-11, 13, 14) 



Staurastrum punctulatum Breb. in Kalfs' Brit. Desm. 1848, p. 133, t. 22, 

 f . 1 ; Arch, in Pritcli. Infus. 1861, p. 740 ; Eabenli. Flor. Europ. Alg. 

 ill, 1868, p. 208 ; Lnnd. Desm. Suec. 1871, p. 63 ; ? Nordst. Desm. 

 Spetsb. 1872, p. 39 ; Norges Desm. 1873, p. 29 ; Desm. Arctose, 1875, 

 p. 34; Kirclm. Alg. Schles. 1878, p. 164; Gay, Monogr. loc. Conj. 

 Montpellier, 1884, p. 66 ; ? Wolle, Desm. U. S. 1884, p. 127, t. 41, f. 43- 

 45 ; Nordst, Desmid. Gronland, 1885, p. 10 ; Cooke, Brit. Desm. 1887, 



