GREEN ALG^. 55 



or eight inches long, either simple or forked. The 

 margin is mostly toothed and frequently undulate. 

 The color is a full grass green, and the plants 

 in my herbarium certainly keep their color much better 

 than the Ulvcz of our coast. My plants adhere well 

 to paper. It is found in abundance at Santa Bar- 

 bara, California, but my correspondents do not else- 

 where report it from that coast. 



Genus.^-FORPBYRA* Ag. 



In structure, as well as in habit of growth, and 



method of reproduction, this Genus agrees very well 



with the Ulva. There is but one species in this 

 genus. 



PORPHYRA VULGARIS, Ag. " LaVER." 



Common everywhere. It is known by its frond 

 of dark purple, thin and somewhat elastic membrane, 

 which has a peculiar sheen like that of satin. This 

 quality of it is retainetl somewhat even when dry, 

 but is very striking and beautiful when the plant is 

 in ilie water. The frond is as variable in form as 

 that of the Ulva, from which it differs mainly in 

 respect to color. I have often found it near low 



* Porphyra = purple-weed- 



