STAURASTRUM. 181 



Devil's Jumps near Frensham) ! Sussex (Ralfs). 

 Kent ! Hants ! (//<>//) Devon ! Cornwall (zy go- 

 spores from Tremethick Moor) ! (Marquand). 



AY ALES.- -Fairly general ! 



SCOTLAND. - General, but rather scarce! (Roy ft 

 .///x.sv//.) Locli More, Sutherland ! Loch Doon, Ayr ! 

 Dumfries ! TVigtown ! Plankton of Orkneys and 

 Shetlands ! Rather rare in general plankton ! 



IBKLAXD. - -Donegal! Mayo (and Clare Island)! 

 Gahvay ! Kerry! Dublin and AYicklow (Archer). 

 Down (up to 2000 ft.) ! Lough Xeagh, Antrim ! 

 Londonderry ! 



Geogr. Distribution.- -France. Germany. Switzer- 

 land. Austria and Galicia. Hungary. Servia. Rou- 



o / 



mania. Italy. Spain. Norway (and Finmark). 

 Sweden. Denmark. Bornholm. Finland. Poland. 

 Russian Lapland. N., Central, and S. Russia. 

 Faeroes. Iceland. Nova Zembla. Spitsbergen. 

 Greenland. Japan. E. India. Ceylon. Java. 

 Australia. New Zealand. Azores. United States. 

 Brazil. Argentina. Patagonia (a form). 



St. punctnlatum is one of the most ubiquitous species of the 

 genus, being almost universally distributed in bogs, marshes, 

 and marshy pools. Its characters are distinctive, although it 

 is subject to considerable variation. The cells are frequently 

 twisted at the isthmus, so that the angles of one semicell are 

 not vertically over those of the other, and in many individuals 

 the twist is fully 60. The semicells are usually triangular in 

 vertical view, but tetragonal forms are by no means rare. 

 The granules are uniform in character and somewhatdepressed, 

 having a disposition in concentric series around the angles, 

 but at the apex of the semicell, and in other parts, they are 

 irregularly scattered. In its most typical form the semicells 

 of St. punctnlatum are on the whole rhomboid-elliptic, with 

 acutely-rounded lateral angles, and the sides of the vertical 

 view are slightly retuse in the middle. 



Some of the specimens recorded by ISTordstedt from within 

 the arctic circle are larger than any British specimen we have 

 yet seen : length up to 52 fjL ; breadth up to 48 /u. 



The smallest forms we have seen were from Lewis, Outer 

 Hebrides ; length 22 breadth 18' o M (PL CXXYII, fig. 12). 



