1919] Setchcll-Garclner : Myxophyceae 49 



Radaisia clavata departs slightly from K. Laminnriac in having 

 the filaments occasionally branched, and the cross cell divisions often 

 decidedly irregnlarh' oblique. 



4. Radaisia epiphytica S. and G. 

 riate 3, figs. 10, 11 



Thalli forming cushions on the surface of the host, nearly circular 

 in outline as seen from above, 250-350/i, across, 50-60/x thick ; prostrate 

 or basal layer formed by dichotomous or subdichotomous branching 

 around the margin ; erect filaments loosely adherent, composed of 

 groups of angular cells, 3-5^ diam., produced by cell divisions in three 

 planes ; protoplast homogeneous, blue-green ; terminal and subterminal 

 cells of the vertical groups transformed into gonidangia with slight 

 increase in size; gonidia angular, 1.8-2.4/x diam., foi'ined by simul- 

 taneous division of the protoplast. 



Growing on Iridaea minor J. Ag. in the lower littoral belt. Carmel, 

 Monterey County, California. 



Setchell and Gardner, in Gardner, New Pac. Coast Alg. II, 1918, 

 p. 447, pi. 37, figs. 10, 11. 



Only a single antheridial i)lant of Iridaea has been observed with 

 tliis epiphyte growing upon it, but doubtless it is common and prob- 

 ably- grows on other forms of the same species. Iridaea minor is 

 usually rather dark colored, which makes the presence of the Radaisiu 

 somewhat obscure, and probably accounts for its not having been 

 observed previously'. 



The gonidangia of R. epiphytica depart somewhat from the typical 

 form of the genus. Since the erect filaments are complex in each 

 sheath, resulting from vertical as well as horizontal divisions, often 

 irregular and oblique, the gonidangia are also complex, consisting of 

 a group of transformed terminal cells instead of a single terminal cell 

 as is usually the case. The original cell wall or sheath persists as 

 the erect filaments elongate and become complex. Likewise when 

 the terminal cells metamorphose into gonidangia the original sheath 

 of a group of cells persists, and a compound gonidangium is the result. 



13. Gomphosphaeria Kuetz. 



Cells associated into definite, small, irregularly more or less 

 .spherical, solid, floating masses ; cells usually obovoid, tapering within, 

 rounded or, at the l)eginning nf division, obcordate without, supported 



