COSMAEIUM. 135 



view of semicell circular. Vertical view elliptic, ratio 

 of axes 1 : 1*71. Cell-wall punctate. Chloroplasts 

 axile, eacli with two pyrenoids. 



Zygospore unknown. 



Length 54 p. ; breadth 48 p. ; breadth of isthmus 

 12 p, ; thickness 28 p.. 



Geogr. Distribution. Sweden. United States. 



The typical form of this species is not known to occur in 

 the British Islands. 



Var. angustatum nob. (PI. LVI, figs. 6, 7.) 



C. obsoletum (Hantzsch) Eeinsch var. angustatum West, Alg. W. Ireland, 



1892, p. 144, t. 24, f. 22. 

 C. obsoletiim var. angustatum West forma galiciensis Gutw. Norm. Alg. 



Nov. 1896, p. 49, t. 7, f. 46. 



A variety with the sinus closed and linear, with the 

 basal angles of the semicells rectangular and the lower 

 part of the sides straight and parallel, and with the 

 apex in the middle subtruncate. 



Length 42 '5-43 '5 //,; breadth 34-37 p. ; breadth of 

 isthmus 11-14 p.. 



IRELAND. Carrantuohill, Kerry ! 



Geogr. Distribution. Gralicia in Austria. 



The Desmid described as Cosmarium obsoletum var. angus- 

 tatum is much better referred to C. Smolandicum Lund. We 

 have examined further specimens from Carrantuohill and find 

 that the figure given in the ' Alg. W. Ireland/ tab. 24, fig. 

 22, is not a good one. The basal angles of the semicells are 

 rectangular, and the ruucro at each angle, although less pro- 

 minent than in the type, projects laterally. The upper angles 

 are also more rounded and the apex is more distinctly truncate. 

 Thus, the specimen found by Grutwinski in Austria, which 

 he named ' C. obsoletum var. angustatum forma galiciensis,' 

 and about which he remarks : " a forma irlandica diff ert 

 angulis basalibus alias protractis, angulis superioribus magis 

 rotundatis vel oblique truncatis," must also be referred to C. 

 Smolandicum var. angustatum. Gutwinski's measurements 

 of his Austrian specimens (length 40-43 fj. ; breadth 30'4-35 

 /j. ; breadth of isthmus 11-13 ju) agree almost exactly with the 

 dimensions of the Irish forms. 



