GREEN ALG^. 53 



shape, varying in respect to the former from two to 

 twelve inches in width, and from six to twenty-four 

 and thirty-six inches in length. And in respect to 

 the latter, it is sometimes simple, and sometimes 

 lobed, sometimes plain, and as broad as long, some- 

 times long ruffled, or plaited on the edge. The 

 substance of the frond is thin and soft, and very 

 smooth and glossy, like silk. The color is a brilliant 

 green, being darker the deeper the water it grows 

 in. It sometimes turns brownish in the herbarium. 

 It is often found pierced with holes, the results either 

 of age or of the attack of snails. It is an annual, 

 but is often found in winter. It grows in pools and 

 below low-tide mark. It is so common everywhere 

 that I need not give special habitats. 



Var. Linza L. — This is a charming and interesting 

 plant. Starting from a minute "hold-fast," as we 

 call the root, or place of attachment of the plant in 

 Algae, it gradually expands to the breadth of an inch 

 or more, and rises to the height of six or eight inches. 

 The edges are full or ruffled, so that when 

 spread out on paper, the plant seems plaited all 

 down the sides, and the full grass green color of the 

 frond is deepened at every plait. Our figure, Plate 

 II., gives a very good account of it. It is quite 

 common along our rocky shores northward, adheres 



