STAURASTEUM. 185 



PL CLIV, fig. 9 is the form of St. monticulosum frequently 

 encountered in Britain. It is a form of var. bifarium Xordst., 

 but is not identical with Xordstedt's plant, since the lower whorl 

 of processes is very feebly developed, being represented merely 

 by pairs of spines. It resembles in some respects var. groen- 

 landicum Gronbl. 



Var. groenlandicum Gronblad. (PI. CLIV. fig. 10.) 



St. megatonotum forma Xordst. Desm. Groenl. 1885, p. 11. t. 7, f. 1, 8 ; 



West, Alg. W. Ireland, 1892, p. 17.3, t. 23, f. 1. 

 St. monticulosum Roy & Biss. Scott. Desm. 1893, t. 3, f. 4. 

 St. monticulosum var. groenlandicum Gronblad, Desm. Keuru. 1920, p. 88, 



t. 1, f. 17, 18. 



Very similar to var. bifarium Xordst. ; apical and 

 lower series of prominences, however, considerably 

 reduced, and provided with one spine each instead of 

 two ; vertical view with four slight prominences in each 

 lateral margin apart from the apical processes, the 

 median pair being, however, larger than the outer two ; 

 granulation round the angles stronger than in the other 

 forms. 



Length, including processes, 46-50 u. : breadth, in- 

 cluding processes, 46-50 ^ ; breadth of isthmus, about 



SCOTLAND. --Bet ween Bishop's Dam and Clochnaben, 

 Kincardine. 



IRELAND. - -Nacoogarrow Lough, Galway ! Carrantuo- 

 hill, Kerry ! 



Geogr. Distribution. Greenland. Finland. 



Var. pulchrum AV. & C4. S. West. (PL CLIV, fig. 12.) 



St. monticulosum var. pukhnun West & G. S. West, Alg. X. Ireland, 11)02, 

 p. 47, t. 2, f. 28; Gronblad, Desm. Keuru, 1920, p. 90. 



Smaller and more delicate than the typical form, 

 processes at the angles much more slender, solid, and 

 emarginate at their apices, with a pair of slender and 

 longer spines above each angle. 



Length, without spines, 23 [i ; including spines, 29 [JL ; 

 breadth, without spines, 21 [/. ; including spines, 28 ^ ; 

 breadth of isthmus 8 [i. 



IRELAND. --Lough Gatny, Donegal ! 



