126 BEITISH DESMIDIACEjE. 



Var. ITALICUM (Nordst.) St. amoenum var. italic-urn Nordst. 

 Desm. Ital. 1876, p. 43, t. 13, f. 18. Semicells with a convex 

 apex, granules of upper part of semicell all arranged on small 

 flattened warts which are well seen in the vertical view ; 

 basal part of semicell triangular, angles granulate and with 

 a small granulate tumour in the middle of each side. Length 

 31 JJL ; breadth of base of semicell 20 ju, of apex 28-30 JJL ; 

 breadth of isthmus 18 fj.. Italy. 



Var. ACANTHOPHOEUM (Nordst.) St. amoenum subsp. acaii- 

 thopliorum Nordst. 1. c. t. 13, f. 19. Each basal verruca 

 furnished with a pair of sharp spines ; granules of upper part 

 of semicells very acute and with a tendency to be arranged 

 on flattened warts. Length 38 /m ; breadth of base of semi- 

 cell 19 fjL, of apex 24; breadth of isthmus 14 /u. Italy. 

 Austria (Tyrol and Bohemia) . 



Var. TUMIDIDSCULUM (Nordst.) St. amoe.num var. tumidius- 

 culum Nordst. in Bot. Notiser, 1887, p. 158 ; Freshw. Alg. of 

 N. Zeal. 1888, p. 38, t. 4, f. 13. Apical angles inclined to be 

 verruculose rather than granulate or denticulate; vertical 

 view quadrangular with straight sides and slightly dilated 

 angles. Length 45 /z; breadth of apex (max.) 40 /m; breadth 

 of isthmus 24 //. New Zealand. We have given a figure of 

 this variety for comparison with var. spet slier gense (PL CXVIII, 

 fig. 9). 



Var. spetsbergense (Nordst.) Cooke. (PL CXVIII, 



fig. 8.) 



St. Capitulum var. amoenum forma spetsbergensis Nordst. Desm. Spetsb. 



1872,, p. 39, t. 7, f . 25 [figures not quite correct according to Nordstedt] ; 



Larsen, Ferskvandsalg. Vest-Gronl. 1907, p. 348. 

 St. amoenum forma spetsbergensis Nordst. Desm. arct. 1875, p. 36 ; Boldt. 



Desm. Gronl. 1888, p. 39 ; Roy & Biss. Scott. Desm. 1893, p. 178 ; Borge, 



Sussw. Chlor. Archang. 1894, p. 37. 

 St. Capitulum var. spetsbergense (Nordst.) Cooke, Brit. Desm. 1887, p. 161, 



t. 55, f. 3. 



With the sharp granules (or clenticulations) of the 

 upper angles fewer in number and more irregularly 

 disposed. 



Length 34-45 ^ ; breadth of base of semicell 

 26-28 /x, of apex 31-33 p; breadth of isthmus 

 12-20 p.. 



ENGLAND. Blea Tarn, Westmoreland (Bissett). 



WALES.- -Capel Curig and Pen-y-gwryd, Carnarvon- 

 shire (Roy). 



