84 BRITISH DESMID1ACEJE. 



Length lO'o-12'o /A; breadth at apex of semicells 

 10'5-12'5 /x ; breadth of isthmus 6*5 /x; thickness 

 7'5-8'5/x. 



SCOTLAND. Small pool on the north side of Loch 

 Dawin, Cromar, Aberdeen (Roy SfBissett). 



Geugr. Distribution. Poland. Gralicia in Austria. 



104. Cosmarium abbreviatum Racib. 

 (PL LXXII, figs. 9-11.) 



Cosmarium abbreviatum Bacib. Noun. Desm. Polon. 1885, p. 83, 1. 10, f . 13 ; 

 De Toni, Syll. Alg. 1889, p. 950 ; Schmidle, Chlorophy.-Fl. Torfstiche 

 Virnheim, 1894, p. 56 ; Eoy & Biss. Scott. Desm. 1894, p. 40 ; Norclst. 

 Index Desm. 1896, p. 36 ; West & G. S. West, Alar. S. England, 1897 y 

 p. 486 ; G. S. West, Alga-fl. Cambr. 1899, p. 216 ; West & G. S. West, 

 Alga-fl. Yorks. 1900, p. 92 ; Alg-. N. Ireland, 1902, p. 34 ; Notes Alg. Ill, 

 1903, p. 10 (sep.) ; Scott. Freshw. Plankton, I, 1903, p. 526 ; Freslrw. 

 Alg. Orkneys and Shetlands, 1905, p. 22 ; Further Contrib. Fresher. 

 Plankton Scott. Lochs, 1905, p. 484. 



Ursinella abbreviata Kuntze, Eevis. gen. plant. 1891, p. 924. 



Cells small, about as long as broad or a little broader, 

 deeply constricted, sinus narrowly linear with a slightly 

 dilated apex ; semicells transversely elongate-hexagonal, 

 angles slightly rounded, apex broadly truncate, straight 

 or slightly retuse. Side view of semicell subcircular. 

 Vertical view narrowly elliptic, ratio of axes about 

 1 : 2'1. Cell-wall smooth. Chloroplasts axile, with a 

 central pyrenoid. 



Zygospore unknown. 



Length 12'5-22 /x; breadth 13-22 /,.; breadth of 

 isthmus 2-7 /A ; thickness 7'2-9'5 /*. 



ENGLAND. Brothers' Water, Westmoreland ! Hamps- 

 fell, Lancashire ! Pilmoor, IV. Yorks ! Skipwith Com- 

 mon, E. Yorks ! Epping Forest, Essex ! Ely, and be- 

 tween March and Guyhirne, Cambridge ! Ux bridge, 

 Middlesex ! Enbridge Lake, Hants. (Roy}. Xear 

 Crowan, Cornwall ! 



WALES. Llyii-y-cwm-ffynon, Llyii Ogwen, and 

 Capel Curig, Carnarvonshire ! 



SCOTLAND.- -Loch Kinellan, Ross ; Brin, Inverness ; 

 Xairn ; Scotston, Birsemore, Heugh-head, Milton Moor. 

 Culblean, and Lochnagar, Aberdeen; Nigg, Cammie, 



