150 BEITISH DESMIDIACE.E. 



C. crenatum Ralfs var. alpinum Racib. is unquestionably 

 the same Desmid as C. undulatum Corda var. minutum Wittr., 

 and should without doubt be regarded as a variety of C. 

 undulatum. It differs from the typical form of that species 

 in the shape of the semicells and in the more numerous 

 undulations. 



Yar. crenulatum (Nag.) Wittr. (PL LIX, 



figs. 11, 12.) 



? Euastrum, crenulatum Ehrenb. 1839. 



E. (Cosmarium) crenulatum Nag. Gatt. einz. Alg. 1849, p. 120, t. 7 A, f. 7. 



Cosmarium crenulatum Breb. Liste Desni. 1856, p. 131 ; Schniidle, Beitr. 



Algenfl. Schwarzwald. u. Klieineb. 1893, p. 96, t. 4, f . 9 ; Beitr. alp. 



Alg. 1895, p 388. 

 C. bioculatum Breb. b. crenulatum Eabenh. Flor. Eur. Alg. Ill, 1868, 



p. 163 ; De Toni, Syll. Alg. 1889, p. 933. 

 C. undulatum Corda var. crenulatum (Ehrenb.) Wittr. Skanclinav. Desm. 



1869, p. 11 ; Nordst. Desni. Brasil, 1870, p. 210 ; Wittr. Gotl. Ol. sctv. 



Alg. 1872, p. 59 ; Heimerl, Desm. alp. 1891, p. 599. 

 C. Meneghinii Breb. forma crenulata Kichter in Wittr. & Nordst. Alg. 



Exsic. 1883, no. 566 ; Hansg. Prodr. Algenfl. Bohin. 1888, p. 195 ; Hoff 



in Nordst. Bornh. Desm. 1888, p. 197. 



Cells smaller, about 1^- times longer than broad; 

 semicells quadrate-semicircular, with about 8 undula- 

 tions including the basal angles. 



Length 29-30 /*; breadth 22-5-23 //,; breadth of 

 isthmus 7-8*5 ft; thickness 13 /*. 



SCOTLAND. Craig-an-Lochan, Perth ! 



Geogr. Distribution. Germany. Bohemia. Switzer- 

 land. Sweden. Bornholm. Spitzbergen. India. 

 Brazil. 



This variety is distinguished from other forms of C. undu- 

 latum bv the fewer number of undulations on each semicell. 



t/ 



In general aspect it closely resembles C. impressulum Elfv., 

 a species with which it should be carefully compared. 



C'. Meneghinii Breb. forma tricrenata Turn. (Treshw. Alg. 

 E. India/ 1893, p. 71, t, 8, f. 25) is stated by the author to 

 be identical with Euastrum crenulatum Nag., but his figure is 

 much nearer a form of C. impressulum Elfv. 



Var. Wollei West. (PI. LIX, figs. 8-10.) 



C. undulatum Corda var. crenulatum Wolle, Desm. U. S. 1884, p. 67, 1. 16, 



f . 10, 19 : Eoy & Biss. Scott. Desni. 1894, p. 177. 

 C. undulatum Corda var. Wollei West. Alg. W. Ireland, 1892, p. 151. 



