1925J Setchell-Gardner: Melanophyceae 467 



14. Myrionema compsonematoides S. and G. 



Plate 55, fig. 10 



Fronds forming microscopic cushions irregular in outline, 200-400/* 

 diam., prostrate portion composed of distorted filaments; erect fila- 

 ments cylindrical, unbranched, 70-80/t high ; hairs unknown ; cells of 

 creeping filaments considerably irregular in shape and size, 4-6/i diam. ; 

 cells of erect filaments cylindrical, 5-7/x diam., quadrate; "ascocysts" 

 sparse, terminal or at times lateral near the base of the erect filaments; 

 gametangia fusiform to clavate, sessile or short-pedicellate, 50-65/;. 

 long, 7-10/i broad ; loeuli uniseriate below, biseriate above. 



Growing on the blade of Lamina ria complanata. Friday Harbor, 

 Washington. 



Setchell and Gardner, Phyc. Cont. 1 1, 1922, p. 343, pi. 34, fig. 10. 



Myrionema compsonematoides seems to be a modification of M. 

 foecwndum. There is a slight sterilization of tissue in that a few of 

 the erect filaments remain sterile and develop slightly beyond the 

 gametangia, and in that a part of the gametangia are pedicellate. It 

 seems to tend toward Compsonema in these respects, and in having 

 biseriate gametangia in part. 



15. Myrionema hecatonematoides S. and G. 



Plate 55, fig. 11 



Fronds forming thin light brown cushions, more or less circular 

 in outline, up to 6 mm. diam. ; prostrate portion composed of distorted, 

 irregularly radiating filaments, mostly monostromatic, in part distro- 

 matic, producing a few penetrating peg-like rhizoids below; erect 

 filaments unbranched, cylindrical, 240-260/t long ; true hairs absent ; 

 cells of erect filaments 6.5-7. 5/* diam., 2-3 times as long; zoosporangia 

 unknown ; gametangia sessile or on 1-2-celled pedicels on the creeping 

 filaments, cylindrical to fusiform, 45-55/* long, 7-8. 5/t broad ; loeuli 

 mostly uniseriate, biseriate in widest part of the gametangia. 



Growing on the pneumatocysts of Nereocystis Luctkeana. Pacific 

 Grove, California. 



Setchell and Gardner, Phyc. Cont. II, 1922, p. 343, pi. 34, fig. 11. 



As indicated by the partially distromatic base, the slight tendency 

 to biseriate loeuli in the gametangia, and the sterilization of a part 

 of the erect filaments, this species of Myrionema seems to be differen- 

 tiating in the direction of the genus Heeatonema. We are retaining 



