252 BRITISH DESMIDIACEJE. 



named u C. Rostafinskii var. americamim'* (vide W. & G-. S. 

 West, 'Some Desm. U. S.' 1898, p. 304, t. 17, f. 13). This 

 differs from the usual form in the absence of the granules 

 above the isthmus, and should be placed as C. speciosum var. 

 Rostafinskii forma americana. 



212. Cosmarium subspeciosum Nordst. 

 (PI. LXXXIX, fig. 11.) 



Cosmarium subspeciosnm Xorclst. Desm. Arctoa?, 1875, p. 22, t. 6, f. 13 ; 

 Cooke, Brit, Desm. 1887, p. 117, t. 41, f. 2 ; Boldt, Desm. Gronland, 1888, 

 p. 20 ; De Toni, Syll. Alg. 1889, p. 986 ; West, Alg. N. Yorks. 1889, 

 p. 293 ; Alg. N. Wales, 1890, p. 290 ; Alg. W. Ireland, 1892, p. 159 ; 

 Alg. Engl. Lake Distr. 1892, p. 729 ; Eoy & Biss. Scott, Desm. 1894, 

 p. 175 ; Borg. Ferskv. Alg. Ostgronl. 1894, p. 16 ; Nordst, Index 

 Desm. 1896, p. 247 ; West & G. S. West, Welw. Afric. Fresh AV. Algae, 

 1897, p. 175 ; Borg-e, Trop. n. snbtrop. Stissw.-Chlor. 1899, p. 23 ; West 

 & G. S. West, Alga-fl. Yorks. 1900, p. 85 ; Alg. N. Ireland, 1902, p. 40 ; 

 Fresliw. Alg. Orkneys and Shetlands, 1905, p. 22 ; Borge, Beitriige Alg. 

 Schweden, 1906, p. 42. 



Ursinella subspeciosa Kuntze, Eevis. gen. plant. 1891, p. 925. 



Cells rather under medium size, lj-1-g- times as long- 

 as broad, deeply constricted, sinus narrowly linear ; 

 semicells pyramidate-subsemicircular, from the flat 

 base at first slightly dilated, then very gradually attenu- 

 ated to the subtruncate apex, basal angles scarcely 

 rounded, apical angles slightly rounded, margin 16-18- 

 crenate, 4 apical crenations and 6-7 on each convex 

 side, those crenations near the basal angles smaller 

 than the apical ones, crenations (except those at the 

 basal angles) minutely bigranulate ; within the margins 

 minutely granulate, granules arranged in radial and 

 concentric series, o outer concentric series geminate, 

 2 inner series single ; in the centre above the isthmus 

 with a rounded granulate tumour, granules irregularly 

 disposed or in 5-6 indistinct subvertical series. Side 

 view of semicell ovate-rectangular, slightly tumid at 

 the base on each side, apical angles slightly rounded. 

 Vertical view elliptic, with a tumour at the middle on 

 each side, poles rounded. 



Zygospore unknown. 



Length 41-50-4^; breadth 2S-8-36 p, ; breadth of 

 isthmus 12-16-2; thickness 20-26 p.. 



ENGLAND . Westmoreland ! (///x.sv//). Shipley Glen 



