HYALOTHECA. 233 



Lake Distr. 1892, p. 6 (sep.) ; Roy & Biss. Scott. Desm. 1893, p. 9 (sep.) ; 

 Borge, Sao Paulo Alg. 1918, p. 77. 



The cells are provided with small inflations at the 

 base of the semicells, which are seen best in the end view 

 as prominences at the two opposite poles of the nearly 

 circular cell. 



Length 16-33 JJL ; breadth 21-36 p. ; thickness 18-33 JJL. 



ENGLAND.- -Near Ditton Farm, Surrey ! Enbridge 

 and Milford Lakes, Hants (Roy). 



SCOTLAND. Common (Roy & Biss.). 



IRELAND.- -Lough Guitane, Kerry ! 



Geoyr. Distribution. Germany. Switzerland. Galicia 

 in Austria. Norway. Sweden. Finland. Nova Zembla. 







Spitsbergen. Greenland. Burma. New Zealand. Brazil. 



This form is probably more general in the British Isles than 

 would appear from the above localities given, but it is difficult 

 to recognise except in the end view. 



Forma tridentula Nordst. (PL CLXI, fig. 21.) 



//. dissiliens f. tridentula Xorclst. Xorges Desm. Ls7.'>. p. 48, t. 1, f. 23; 

 Boldt, Desm. Gronland, 1888. p. 43 Xordst. Freshw. Ale. X. Zealand, 

 1888, p. 27 ; Roy & Biss. Scott, Desm. 1893, p. it : West & G. S. West, 

 Alg. S. England," 1897, p. 497; Alga-n. Yorks. 1902. p. Ill; Alg. X. 

 Ireland, 1902, p. 60 ; Alg. Orkneys and Shetland*, 1905, p. 28. 



H. dissiliens f. triquetra Jacobs. Desm. Danem. 187"), p. 213, t. 8, f. 29. 



Semicells with 3 small basal inflations visible as tiny 

 mamillse at equal distances in the end view. 



Length 18-24 pi ; breadth 26-37 u. 



ENGLAND. Cronkley Fell, N. Yorks ! Sutton Park, 

 Warwicks ! Esher West End Common, Surrey ! 

 Enbridge and Milford Lakes, Hants (Roy). Wilts ! 

 Halo;avor and Lanliverv Moors, Cornwall ! 



c^ / 



SCOTLAND. General ! In the plankton ! Lough near 

 Cearnabahl, Lewis, Outer Hebrides ! Shetlands ! 



IRELAND.- -Donegal (zygospores from Lough Nacung)! 

 Oalway ! Kerry ! 



Geogr. Distribution. Galicia in Austria. Hungary. 

 Italy. Portugal. Norway. Sweden. Finland. Spitz- 

 bergen. Greenland. India. Burma. New Zealand. 

 'Colombia. Argentine. 



