MICRASTER1AS. 101 



Var. brachyptera (Lund.) nob. (PL XL VI, fig. 5 ; 



PI. XL VII, figs. 6, 7.) 



.V. brachyptera Lund. Desm. Suec. 1871, p. 12, t. 1, f. 4; Wolle, Desm. 



U.S. 1884, p. 110, t. 32, f. 6, 7 ; Biss. Desm. Windermere, 1884, p. 192 ; 



Cooke, Brit. Desni. 1886, p. 63, t. 30, f. 2; De Toni, Syll. Alg. 1889, 



p. 1120. 

 If. brachyptera forma bispinata Turn. New and Rare Desm. 1885, p. 937, 



t. 16, f. 15. 

 If. apiculata (Ehreiib.) Menegli. subsp. fimbriata y brachyptera Nordst. 



Bornh. Desm. 1888, p. 190. 

 Helierella brachyptera Kuntze, Revis. gen. plant. 1891, p. 898. 



Proportionately longer than the type; polar lobe 

 more projecting, relatively larger and wider, with a 

 distinct constriction below the apex, apical margin 

 widely retuse ; lateral lobes shorter and generally with 

 fewer lobulations ; sinus and incisions between the 

 lobes widely open, especially the incisions between the 

 polar lobe and the superior lateral lobes; generally 

 with a row of spines bordering each side of the polar 

 lobe and the sinus. Cell-wall punctate. 



Length 191-230 p.; breadth 131-180 //,; breadth of 

 isthmus 34-37 ft,; max. breadth of polar lobe 54-60 p.; 

 thickness 72 p. 



ENGLAND. Bowness, Westmoreland! (Bissett). 



SCOTLAND. - - Loch Ness, Inverness ! Rhiconich, 

 Sutherland ! Plankton of Loch Fadaghoda, Lewis, 

 Outer Hebrides ! 



Geoyi'. Distribution. Norway. Sweden. Poland 

 (form). S. Russia. United States. 



This is a well-marked variety of J/. apiculata differing in 

 its shorter lateral lobes, wider and more outstanding polar 

 lobe, and in the fewer number of surface-spines. The inser- 

 tion of the marginal spines is exactly similar to that of all 

 other forms of J\I. apiculata, and the lobulation of the lateral 

 lobes and number of inserted spines is very variable, the two 

 semicells of one individual often differing considerably in 

 these respects. There is thus no reason for Turner's name 

 "forma bispinata." Most specimens of this variety possess a 

 row of spines within each side of the polar lobe and within 

 each margin of the sinus. The number of these spines is 

 variable and in some specimens they are entirely wanting. 



