EUASTEUM. 69 



England, 1897, p. 4S4 ; Alga-fl. Yorks. 1900, p. Go ; Chlorophy. Koh 

 Chang, 1901, p. 85 ; Alg. N. Ireland, 1902, p. 2U ; Freshw. Alg. Ceylon 

 1902, p. 15G. 



Cosmarium insnlare (Wittr.) Schmiclle, Chlorophy-Fl. Torfstiche Virn- 

 heim, 1S94, p. 59. 



Cells minute, 1-J- times longer than broad, deeply 

 constricted, sinus narrowly linear, with a dilated ex- 

 tremity ; semicells three-lobed, interlobular incisions 

 subrectangular ; polar lobe widely rectangular, angles 

 rounded, apex truncate and retuse-emarginate in the 

 middle ; lateral lobes short, basal angles subrectangular, 

 sides slightly retuse. Side view of semicell ovate, with 



O i/ . 



a slight protuberance on each side. Vertical view 

 elliptic, with a very slight protuberance at the middle 

 on each side. Cell- wall smooth. 



Zygospore unknown. 



Length 17'5-30/x; breadth 1 1-5-22 //,; breadth of 

 isthmus 3*3-6 ft ; thickness 9'5-11'Ofi. 



ENGLAND. Westmoreland! (Bissett). N. Yorks! 

 Lincolnshire ! Cambridgeshire (Wicken Fen) ! Hants ! 

 (Rot/). Devon ! Cornwall (Bennett). 



WALES. Llyn Bodrie, Anglesey ! Frequent in 

 Carnarvonshire ! 



SCOTLAND.- -Sutherland ! Ross ! Inverness, Aber- 

 deen, Kincardine, Forfar, Perth !, Argyll (Roy $ 

 Bissett). Outer Hebrides! 



IRELAND.- -Xear Grlenties, Loughs Anna and Akibbon, 

 Donegal ! Lower Lake of Killarney, Kerry ! Dublin 

 and Wicklow (Archer). Lough Derryadd, Armagh! 



(ii'nijr. Distribution. Galicia in Austria. Norway. 

 Sweden. Siam. United States. 



This small and characteristic species is widely distributed 

 and sometimes occurs in abundance. It was originally 

 described as a variety of Euastmm binale, but the distinctly 

 three-lohed semicells and the rectangular basal angles suffi- 

 ciently characterize it. 



A form of it was described from Cambridgeshire (vide 

 G. S. West, 'Alga-fl. Cambr/ 1899, p. 114, t. 396, f. 11) in 

 which the lateral lobes were less rectangular and almost 



*_j 



bilobulate. Length 28 /UL ; breadth 19 /t breadth of isthmus 

 5 M ; thickness 11 /UL (PL XL, fig. 14). 



