184 BRITISH DESMIDJA6JEJE. 



to the basal angles and the apical region ; with about 

 3 oblique series of granules across each basal angle 

 (5 visible at the margin), and with about 6 short 

 oblique series within the apex (5-6 visible along the 

 flat apical margin) ; in the centre of the semicells with 

 a tumour furnished with a rino; of 8 granules sur- 



a o 



rounding a larger central one. Side view of semicell 

 subcircular with an inflation on each side towards the 

 base. Vertical view elliptic with a prominent 3-granu- 

 late tumour at the middle on each side, poles granulate. 

 Chloroplasts axile, with one pyrenoid. 



Zygospore globose, furnished with rather delicate 

 processes or spines, dilated at the base, furcate-einar- 

 ginate (sometimes trifurcate) at the apex, and not 

 infrequently bent. 



Length 31-33 ju ; breadth 31-5-35 /i; breadth of 

 isthmus 10-10'4ju; thickness 20-22*5^; cliam. zygosp. 

 without spines 32 /n, with spines 61 /u. 



EXGLAXD. - - Cocket Moss near GrigglesAvick, W. 

 Yorks ! Leicestershire (Roif). Epping Forest, Essex ! 

 Esher AYest-end Common, Surrey (very abundant in 

 1893-4) ! Enbridge Lake, Hants. (Rot/). Xear St. 

 Just, Cornwall ! 



WALES. Near Pen-y-gwryd and Capel Curig, Car- 

 narvonshire (Roy). 



SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine 

 (with zygospores from near Crathes), Forfar, Perth 

 (Ro/i $ Bissett). Kirk wall, Orkneys ! 



IRELAND. Louo-h Glartan, Donegal ! Dublin and 



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Wicklow (Archer). 



Geoff r. Distribution.- -France. Silesia in Austria. 

 United States. 



This characteristic species is very local in its distribution. 

 On two occasions we obtained it in quantity in ditches on 

 Esher West-end Common, Surrey, amongst various filamentous 



t/ ' O 



Conjugates. Messrs. Roy and Bissett were the first to point 

 out its decisive characters and to figure the zygospore. 

 Joshua had previously mentioned (1882) the occurrence of the 

 zygospore near Cirencester, Gloucestershire, but this requires 

 confirmation. 



