454 Vniversiiy of Calif ornia Puhlications in Botany [Vol.8 



better with the Elachistea and Myriactis-groi\i-)S, of the Elachisteaceae 

 in its erect filaments slightly contracted at the base. The various 

 Myrionemataceae are most closely allied to the species of Ralfsia, 

 particularly with those referred to Stragularia. The prostrate basal 

 portion of one or two layers of cells readily distinguishes the members 

 of the Myrionemataceae from those of all other families except those 

 of the simpler Ralfsiaceae. 



IVEY TO THE Genera 



1. Erect filaments free 2 



1. Erect filaments enclosed in a jelly 9. Microspongium (p. 492) 



2. Basal portion monostromatic 3 



2. Basal portion distromatic 8. Hecatonema (p. 488) 



3. Gametangia with locuU uniseriate 6. Myrionema (p. 454) 



3. Gametangia with loculi pluriseriate 7. Compsonema (p. 473) 



6. Myrionema Grev. 



Fronds forming small cushions, circular to ellipsoidal, or even 

 quite irregular in outline, composed of a monostromatic basal stratum 

 and numerous pigment-bearing erect filaments with or without hairs 

 interspersed ; the erect filaments in part or wholty transformed into 

 gametangia, except at the margins ; basal stratum composed of closely 

 crowded filaments radiating from a common center, with dichotomous 

 branching by splitting of the terminal cells, rarely with a few, short, 

 subulate branches penetrating the host ; reproduction by unilocular 

 zoosporangia and by plurilocular gametangia mostly with uniseriate 

 loculi. 



Greville, Scottish Crypt. Flora, vol. 5, 1827, pi. 300. 



The type species of this genus is M. strangulans Grev. The type 

 locality is the shore of Appin, Scotland. It was first brought to 

 notice by Captain Carmichael, who found it growing on a small species 

 of Salenia (Enteromorpha) , which it usually completely encircles. 

 Greville says of his genus: "It evidently belongs to the Nostochinae 

 of Agardh. " Although it is undoubtedly known today to belong to 

 the Melanophyceae, there has been considerable diversity of opinion 

 concerning the family to which it properly has its closest affinities. 

 Harvey (1841, p. 124) placed it among the Chlorospermeae, under 

 the tribe Chaetophoroideae, probably on account of its "gelatinous" 

 nature as suggested by Greville. He states, however, that it is "a 

 genus of doubtful affinity," and "it rather belongs to the series 

 Melanospermeae. " J. G. Agardh (1848, p. 47) placed it in his order 

 Chordarieae under his tribe Mesogloiaceae. Kjellman (1890, p. 40) 



