380 University of California Publications in Botany [Vol. 7 



cell splits, one of the dichotomy very frequently fails to develop till 

 much later. IMany of the cells in the center, and even toward the 

 periphery, divide radially and perpendicular to the surface of the 

 host, forming a pseudoparenchymatous layer. Thus this species, 

 strictly speaking, cannot be said to be distromatic, since the distromatic 

 condition of a frond is really brought about by radial divisions of the 

 cells of filaments, but parallel to the surface of the host. The character 

 of the gametangia and of the creeping filaments will not permit of its 

 being placed with Myrionema vulgare Thuret as further described and 

 figured by Sauvageau (1897, p. 186, et seq.). On account of the radial 

 divisions of the creeping filaments and the prevailing biseriate con- 

 dition of most of the gametangia, we are placing this species with the 

 genus Hecatonema and dedicating it to Professor A. A. Lawson, one 

 of the collectors. 



LITERATURE CITED 



Sauvageau, C. 



1897. Sur quelques Myrionemacees. Ann. sci nat., 8 ser., Bot., vol. 5, pp. 161- 



288. 



Setchell, W. a., and Gardner, N. L. 



1903. Algae of Northwestern America. Univ. Calif., Publ. Bot., vol. 1, 

 pp. 165-418, pis. 17-27. 



