COSMARIUM. 139 



We have never seen any Cosmarium which we could 

 identify with certainty as C. intermedium Del p. It appears 

 to be very closely related to, if not a form of C. Botrytis, and 

 we have reason to doubt the accuracy of Delponte's figure?. 

 The granulation of many of Delponte's figures has un- 

 doubtedly been inserted without any careful reference to the 

 specimens. 



142. Cosmarium cristatum Ralfs. 

 (PI. LXXVI, fig. 11.) 



Cosmarium cristatum Ralfs, Brit. Desm. 1848, p. 105, t. 17, f. 2; Arch, in 

 Pritch. Infus. 1861, p. 734, t. 1, f . 4 ; Eabenh. Flor. Europ. Alg. Ill, 

 1868. p. 172 ; Cooke, Brit. Desm. 1887, p. 114, t. 40, f . 6 ; De Toni, Syll. 

 Alg. 1889, p. 1051; West, Alg. X. Wales, 1890, p. 290; Eoy & Biss 

 Scott, Desm. 1894, p. 44 ; Nordst. Index Desm. 1896, p. 89 ; West & 

 G. S. West, Alg. S. England, 1897, p. 491. 



Ursinella cristata Kiintze, Revis. gen. plant. 1891, p. 924. 



Cells small, very little longer than broad, deeply 

 constricted, sinus narrow and linear, but not quite 

 closed ; semicells almost semicircular, basal angles not 

 rounded, margin furnished with 14-16 short and equi- 

 distant papillae, centre of semicell with a protuberance 

 ornamented with a circlet of 8 granules surrounding 

 one central granule. Vertical view narrowly oblong, 

 with subtruncate poles, at the middle on each side with 

 a broad protuberance showing about 4 granules. 



Zygospore unknown. 



Length 36-37 p.; breadth 34'5-36/x; breadth of 

 isthmus 10-10'5/x; thickness 15'5/x. 



ENGLAND.- -Xear Ambleside, Westmoreland (Ralfa). 

 Furness Fells and Wetherlam, Lancashire (Bennett). 

 Thursley Common, Surrey ! Cornwall (Bennett). 



WALES.- -Capel Curig, Carnarvonshire! 



SCOTLAND. Glen Tanner, Aberdeen ; Cammie, Kin- 

 cardine (Roij $ Bissptt). Ben Lawers, Perth ! 



IRELAND. Derryclare Lough, Galway ! Castletown, 

 Kerry ! Dublin and Wicklow (Archer). 



Geogr. Distribution . France. Germany. Hungary. 



This characteristic species appears to be exceedingly rare. 

 We have only met with it five times, and on each occasion a 

 solitary specimen only was observed. 



