210 BRITISH DESMIDIACE.E. 



Zygospore with shorter 2-3 -furcate spines, and 

 with a ring of 5-6 prominent teeth around the base 

 of each spine. 



Forma o. 

 C. subpunctulatum Nordst. 1. c. 



Apex of semicells smooth. 



Length 29-34 ILL ; breadth 26-32 p breadth of isthmus 

 8 12 /LI ; thickness 17 lS'5/.i; diam. zygosp. without spines 

 about 30 fi, with spines 49 ju . (PI. LXXXIV, figs. 15-20.) 



Forma /3. 



C. subpunctulatum forma Borg. Bornliolm. Desm.-fl. 1889, p. 14-4, t. 6, 

 f . 4 ; Anderss. Sverig. Chlorophy. 1890, p. 15; Borg. Fresliw. Alg. 

 Faeroes, 1901, p. 226. C. subpunctulatum var. Borgesenii West, Alg. 

 W. Ireland, 1892, p. 154 ; Alg. Engl. Lake Distr. 1892, p. 727 ; 

 Schmidle, Variabil. Cosmar. 1893, p. 109 ; West & G-. S. West, Alg. 

 S. England, 1897, p. 488; Alga-fl. Yorks. 1900, p. 76. C. sub- 

 punctulatum forma Bornholmense Liitkem. Desm. Attersees, 1893, p. 

 555. C. trachypleurum var. minus Racib., forma Borge, Siisswasser. 

 Chlor. Archang. 1894, p. 28, t. 2, f. 30. C. KarlinsUi Gutw. Nagj. 

 dosel. Bosui Hercegovin. halugam. 1896, p. 375, t. 1, f . 6. 



Apex of semicells more or less distinctly granulate. 

 Length 29-33 /i ; breadth 26-30 JJL ; breadth of isthmus 

 9-11 M ; thickness 19-21 ^ (PL LXXXV, figs. 1-3.) 



The two forms a and /3 are connected by various inter- 

 mediate states, and in the following localities and distribution 

 they are not discriminated. 



ENGLAND. Langdale, Westmoreland ! Hawkshead 

 and bogs about Cockley Beck, Lancashire ! Culling- 

 worth, W. Yorks ! E. Yorks ! Strensall, K". Yorks ! 

 Frensham Little Pond, near Chapel Wood, and 

 Thnrsley Common (with zygospores), Surrey ! Hants ! 

 (Roy). Cornwall! 



WALES. Rhyddu, Llyn Gwynant, and Capel Curig, 

 Carnarvonshire ! Radnor ! 



SCOTLAND.- -Grlen Garry (It try fy Bis sett), and Craig-an- 

 Lochan, Perth ! Wigtownshire (Itoy fyBissett). Lewis 

 and Harris, Outer Hebrides ! Orkneys ! Shetlands ! 



IRELAND. Dungloe, near Gleiitornan, and Lough 

 Machugh, Donegal ! Near Westport, Mayo ! Lakes 



between Clifden and Roundstone, and Ballynahinch. 



/ 



Galway ! Slieve Donard, Down ! 



