168 BRITISH DESM1DIACE.H. 



ENGLAND.- -Buttermere, and Blea Tarn in Borrow- 

 dale, Cumberland ! Near Ambleside, Westmoreland ! 

 Crirnsworth Dean, W. Yorks ! Wimbledon Common, 

 Surrey ! 



WALES. Bog above Capel Curig Lakes, Llyn 

 Gwynant, Yr Orsedd, and Y Foel Fras, Carnarvon- 

 shire ! Ffestinioo% Merioneth ! 



o - 



SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine, 

 Forfar, Perth, and Wigtown (Roy $ Bissett). Caith- 

 ness ! 



IRELAND. --Gortahork, Donegal! Cloonee Lough, 

 Kerry ! Dublin and Wicklow (Archer). Slieve Donard, 

 Down (up to 2000 ft.) ! 



Geoyr. Distribution.- -Germany. Austria (Tyrol). 

 Italy. Bornholm. Poland. Central Africa. West 

 Indies. 



St. turgescenfi is a, somewhat uncommon species easily dis- 

 tinguished hy the elliptic or elliptic-oblong semicells and the 

 broadly-rounded angles. The granulation is dense, hut the 

 granules have no definite arrangement. It is probably most 

 nearly related to St. alternans. 



The chloroplasts, according to Archer, are axile, with a 

 number of irregular, divergent lobes somewhat like those 

 which are found in the genus Cylindrocystis. 



Archer found the zygospore of this species in Ireland 

 (Consult ' Q. J. Micr. Sci. J xviii, new series, 1878,, pp. 105,, 

 106). It is very like those of St. dilatatum and St. striolatnm. 

 He describes it as follows: " circular, compressed (thus 

 shaped like a round cushion); in the broad view the margin 

 is undulate, undulations nine to twelve, smooth ; in the 

 narrow (edp-e) view the zygospore is oblong-elliptic, sides 

 parallel and straight for a notable distance at the middle, 

 then gradually merging into the broadly-rounded extremities, 

 margin smooth; contents at maturity passing into a bright 

 brownish-yellow colour. An inspection of a zygospore in an 

 oblique position, or, better still, of an empty membrane, 

 showed that the undulations at the circumference of the 

 broad aspect were carried onwards over the front surface, 

 and that the elevations converged towards the centre, and at 

 the same time diminished inwards, so as to disappear ere they 

 reached the centre, where the surface appeared flat." 



The smallest recorded form of St. turgescens is from pools 



