108 BRITISH DESMLDIACE^E. 



cave or convex, angles produced to form short thick 

 processes. 



Zygospore unknown. 



Length, without processes, 27-34*5 pi ; with processes, 

 57-71 {JL ; breadth, without processes, about 20-30 [i ; 

 with processes, 63-86*5 (j. ; breadth of isthmus 7*5-13 pi. 



ENGLAND.- -Plankton of Stickle Tarn and Winder- 

 mere, Westmoreland ! 



WALES.- -In the plankton ! 



SCOTLAND. --Plankton of Lochs Shin, Morar and Ruar, 

 Sutherland ! Loch Shiel, Inverness ! Loch Tay, Perth ! 

 Loch Stranabhat and 7 other lochs in Lewis, and in Loch 

 a Bhursta, Benbecula, Outer Hebrides ! Plankton of 

 Loch Kirbister, Orkneys. 



IRELAND. Plankton of Lough Gall, Achill Isle, 

 Mayo ! Kerry ! 



Geogr. Distribution. --Norway. Canada. 



This species may be compared with some forms of St. para- 

 doxum Meyen, but it is readily distinguished by its shorter 

 processes, which are terminated by two large divergent spines 

 in the same vertical plane. 



St. pseudopelagicum var. bifurcation Huitfeldt-Kaas has pre- 

 cisely the same characters as typical St. pseudopelagicum. The 

 form mentioned by the same author as typical St. pseudopela- 

 gicum, the processes of which, according to him, are terminated 

 by 3 spines each, is possibly a form of St. paradoxum Meyen. 

 Some of the British specimens, however, have been observed 

 by Prof. G. M. Smith of Wisconsin, U.S.A., to possess processes 

 which end in 3 spines, and on one occasion the processes were 

 tipped with one spine only. The species has so far only been 

 found in plankton. 



114. Staurastrum inflexion Breb. 

 (PI. CXLIII, figs. 7, 8.) 



Staurastrum inflexum Breb. Liste Desm. 1856, p. 140, t. 1, f. 25 ; Arch, in 

 Pritch. Infus. 1861, p. 742 ; Cooke, Brit. Desm. 1887, p. 169, t. 58, f. 5 ; 

 De Toni, Syll. Alg. 1889, p. 1208; West, Alg. Engl. Lake Distr. 1892, 

 p. 20 ; Roy & Biss. Scott. Desm. 1894, p. 21 ; West & G. S. West, Alg. 

 S. England, 1897, p. 495 ; Alga-fl. Yorks. 1902, p. 105. 



St. margaritaceum var. inflexum Rabenh. Flor. Europ. Alg. 1868, p. 207. 



