1919] Setchell-Gardner : Myxophyceae 9 



Agmenelhnn was published as a genus by de Brebissou in May, 

 1839, with complete diagnosis and naming of the type species, A. 

 quadruplicatum Breb. It seems, therefore, that AgmeneUum is the 

 first valid publication and ought to be adopted, but following the 

 principle enunciated by the various International Congresses that 

 names of undisputed use for a long series of years may be conserved, 

 we have retained Mfrismopedia until proper action may be taken. 



Merismopedia Gardner! (Collins) Setchell 

 Plate 8, fig. 7 



Plants up to 3 cm. or more long, delicate, membranaceous, very 

 irregular in foinn, more or less lacerated and folded, 7-8/a thick; cells 

 closely placed, cylindrical, 6-6.5ju, long, 3.5-4/x in diam. ; protoplast 

 bluish green, homogeneous. 



Floating in pools of salt water, salt marshes of Alameda, Cali- 

 fornia. 



Setchell, in Gardner, Cyt. studies Cyan., 1906, p. 239 {nomen 

 nudum). Prasiola Gardncri Collins, in Colli^is, Holden and Setchell, 

 Phyc. Bor.-Amer. (Exsicc), no. 1185 (1904), Green Alg. N.A., 1909, 

 p. 221 (in note). 



Merismopedia Gardneri has been collected only once in i)ools of 

 salt water on a marsh in Alameda, California, but it was plentiful at 

 that time. Since then the type locality has been filled in wdth earth. 

 It showed a remarkable resemblance to species of Prasiola, but was 

 decidedly of a more bluish tint, which is even more pronounced in 

 dried specimens. The cytological structure agrees well with that of 

 other Myxophj^ceae and lacks the characteristics of the cells of 

 Prasiola. It is gigantic for a Merismopedia, surpassing even the 

 Merismopedia convoluta Breb., hitherto known as the largest member 

 of the genus. 



4. Chroococcus Naeg. 



Cells single or united into small colonies of 2, 4, or 8 cells, spherical, 

 or more or less flattened when in colonies ; contents blue-green, violet 

 or yellowish ; tegument comparatively thin although distinct, firm, 

 uniform or nearly so, not gelatinous, that of the original cell enclosing 

 the entire small colony; division in three planes. 



Naegeli, Gatt. einz. Alg., 1849, p. 45. 



