00 WUT1SH JDESMIDIACE.E. 



82. Cosmarium plicatum Reinsch. 

 (PI. LXX, figs. 9, 10.) 



plicatum Reinsch, Spec. Gen. Alg. 1867, p. 114, t. 22, f. C. II ; 

 Cooke, Brit. Desm. 1886, p. 81, t. 36, f . 3 ; West, Alg. N. Wales, 1890, 

 p. 288 ; Heimerl, Desm. alp. 1891, p. 596 ; West, Alg. Engl. Lake Distr. 

 1892, p. 723 ; Roy & Biss. Scott. Desm. 1894, p. 171 ; Nordst. Index 

 Desm. 1896, p. 202 ; West & G. S. West, Alga-fl. Yorks. 1900, p. 90. 

 Didymidium (Cosmarium} plicatum Reinsch, Algenfl. Frank. 1867, p. 109, 

 t. 9, f. 1 a-c. 



Cells moderately large, about If-lf as long as 

 broad, fairly deeply constricted, sinus narrow with a 

 slightly dilated apex; semicells truncate-pyramidate, 

 sides slightly convex, rarely almost straight, both 

 lower and upper angles rounded, apex slightly convex. 

 Side view of semicell elliptic. Vertical view elliptic, 

 ratio of axes about 1 : 1 "6. Cell- wall minutely and 

 densely punctate. 



Zygospore unknown. 



Length 48-01 ^ ; breadth 26-35 JJL ; breadth of 

 isthmus 16*5-18 p.. 



ENGLAND.- -Xear Blea Tarn, Cumberland ! Blubber- 

 houses (IF. B. Turner) and Adel Bog!, W. Yorks. 

 Mickle and Great Shunnor Fells, N. Yorks ! 



WALES. - - Snowdon, Llyn Bochlwyd, and Llyn 

 Idwal, Carnarvonshire ! 



SCOTLAND.- -Ross; Brin, Inverness; Brimmond and 

 Dalbargie, Aberdeen ; Pitreddie and Curran, Kincar- 

 dine ; Methen Bog, Perth (Roy fy Bissett). 



IRELAND.- -Dublin and Wicklow (Archer). 



G-eogr. Distribution. --Germany. Sweden. 



C. plicatum is nearest to C. quadratum, hut differs in the 

 more rectangular semicells,, with convex sides,, and in the 

 closed sinus. 



Forma major Reinsch. (PI. LXX, fig. 11.) 



C. plicatum forma A. majus Eeinscli. Spec. Gen. Alg-. 1867, p. 114, t. >, 



f. C. II, 10. 

 C. plicatum var. majus Eeinscli (?) in Roy & Biss. Scott. Desm. 1894, 



p. 171, t. 2, f. 1. 



