134 BRITISH DESMIDIACE^;. 



subcircular. Vertical view elliptic, ratio of axes 

 about 1 : 1*5. 



Zygospore unknown. 



Length 43 /x, ; breadth 32 p. ; breadth of isthmus 15 p. ; 

 thickness 21 p. 



SCOTLAND.- -In a quarry, at Corrie, Arran (Bissetf). 



IRELAND.- -Carrantuohill, Kerry ! 



This species should be compared with C. Portianum, from 

 which it is distinguished by the rectangular lower part of the 

 semicells. 



138. Cosmarium Simii Roy & Biss. 



(PI. LXXVI, fig. 2.) 



Cosmarium Simii Koy & Biss. Scott. Desm. 1894, p. 174, t. 2, f . 16 ; Nordst. 

 Index Desm. 1896, p. 234. 



Cells of medium size, about 1^ times longer than 

 broad, deeply constricted, sinus widely open and 

 acute-angled ; semicells subsemicircular from a convex 

 base, basal angles slightly subrect angular. Cell- wall 

 somewhat finely granulate, granules arranged in about 

 15 or 16 vertical rows and about 7 transverse arched 

 rows, about 25 showing along the margin of each 

 semicell. Vertical view elliptic. 



Zygospore unknown. 



Length 5358 jn; breadth 45-50 /x; breadth of isthmus 

 20-22 p.. 



SCOTLAND. Very rare in Corrie Etchachan on Ben 

 Macdhui, Aberdeen (Roy $ Bissett). 



Compare with (7. Corriense and C. reniforme. 



139. Cosmarium cselatum Halfs. 

 (PI. LXXVI, figs. 5-7.) 



Cosmarium cselatum Ealfs, Brit. Desm. 1848, p. 103, t. 17, f . 1 ; Arch, in 

 Pritch. Infus. 1861, p. 734, t. 2, f. 26; Eabenh. Mor. Europ. Alg. Ill, 

 1868, p. 170 ; Lund. Desm. Suec. 1871, p. 33 ; Nordst. Norges Desm. 

 1873, p. 14 ; Kirchn. Alg. Schles. 1878, p. 154 ; Wolle, Desm. U. S. 1884, 

 p. 86, t. 18, f. 46-48 [figures poor] ; Cooke, Brit. Desm. 1887, p. Ill, 

 t. 40, f . 3 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 202 ; De Toni, Syll. 

 Alg. 1889, p. 1007 ; West, Alg. N. Wales, 1890, p. 290 ; Heimerl, Desm. 

 alpin. 1891, p. 595 ; West, Alg. W. Ireland, 1892, p. 158 ; Alg. Engl. 



