XANTHID1UM. 75 



breadth without spines oo 5G /x, with spines 76-88 //, ; 

 breadth of isthmus 13-16/x ; thickness 35-89 ^. 



SCOTLAND.- -Scolty, Kincardine (l\oij $ Bissett). 



Gctxjr. Distribution.- -Italy. 



8. Xanthidium fasciculatum Ehrenb. 

 (PI. CXI, figs. 6-8.) 



Xmithidium fasciculatum Ehrenb. Infus. 1838, p. 147, t. 10, f. 24 b 

 [figure bad] ; Arch, in Pritch. Infus. 1861, p. 736 [in part] ; Arch, in 

 Q. J. Micr. Sci. vi, 1866, p. 273 ; Rabenh. Flor. Europ. Alg-. Ill, 1868 p. 

 223; Lund. Desm. Suec. 1871, p. 75; Lagerli. Bidr. till Amerik. Desm.-fl. 

 1886, p. 245 ; Cooke, Brit. Desm. 1887, p. 131, t. 46, f . 1 ; Hansg. Prodr. 

 Algenfl. Bohin. 1888, p. 192 ; De Toni, Syll. Alg. 1889, p. 918 ; Heimerl, 

 Desm. alp. 1891, p. 595; West, Alg. W. Ireland, 1892, p. 165; Turn. 

 FreshAv. Alg. E. India, 1893, p. 100, t. 12, f. 34 [figure defective] ; Roy 

 Biss. Scott. Desm. 1893, p. 245 ; Nordst. Index Desmid. 1896, p. 122 ; 

 W. & G. S. West, Alg. S. England, 1897, p. 484 : Alga-fl. Yorks. 1900, 

 p. 68 ; ? Borg. Freshw. Alg. Faeroes, 1901, p. 229 ; W. & G. S. West, Alg. 

 N. Ireland, 1902, p. 30 ; Freshw. Alg. Orkneys and Shetlands, 1905, 

 p. 23 ; Further Contrib. Freshw. Plankton Scott. Lochs, 1905, p. 485 ; 

 Borge, Beitrage Alg. Schweden, 1906, p. 28 ; W. & G. S. West, Brit, 

 Freshw. Phytoplankton, etc., 1909, p. 180. 



X. fasciculatum var. polygonum Ralfs in Ann. Mag. Nat. Hist. 1845, p. 466, 

 t. 12, f. Se ; Brit. Desm. 1848, p. 114, t. 19, f. 4. 



Euast rum fasciculatum Kiitz. Phyc. german. 1845, p. 137. 



Didymidium (Xanthidium) fasciculatum Reinsch, Algenfl. Frank. 1867, p. 

 126. 



X. fasciculatum var. ornatum Nordst. Desmid. Gronlaiid, 1885, p. 12, t. 7, 

 f . 10 ; Him, Desm. Finland, 1903, p. 23 ; Borge, Beitrage Alg. Schweden, 

 1906, p. 28. 



Holacanthum fasciculatum Franze in Oesterr. botan. Zeitschr. 1893, p. 384. 



Cells of medium size, about as long as broad (without 

 the spines), deeply constricted, sinus linear, sometimes 

 with a dilated extremity; semicells angular-reniform, 

 margin with six equidistant pairs of simple and often 

 rather short spines, apex subtruncate, central area 

 rather small and slightly protuberant, with a ring of 

 7-10 granules around a central group of 2 or 3 (rarely 

 smooth?). Side view of semicell subcircular, with a 

 slight protuberance at the middle on each side, and a 

 pair of divergent spines at the apical margin. Vertical 

 view elliptic, with a slight protuberance at the middle 

 on each side, and a pair of divergent spines at each 

 pole. 



Zygospore globose, furnished with long, attenuated 

 spines which are bifid at the apex. 



