96 MARINE ALG^E 



GENUS Corallina 



C" Coral-like") 



C. offidnalis, common coralline. Frond grows from a disk in tufts 

 more or less dense. The plant is rigid, and seems like jointed, branched 

 coral. The articulations are cylindrical at the base, wedge-shaped and 

 flattened above. Branches emanate from the top of the articulations. 

 The color varies from reddish-purple to gray-green, and is often bleached 

 white when exposed to the sun. Common in tide-pools and on rocks 

 at low- water mark from New York northward. (Plate XXXVII.) 



GENUS Melobesia 



This genus will attract attention, although it cannot be gathered. 

 It is a thin, brittle, scaly substance of indefinite form, which ex- 

 pands horizontally and resembles a lichen. It forms brown and 

 pink crusts on other algaa and on rocks, stones, and shells. 



ORDER BANGIACEJE 

 GENUS Hangia 



B. fusco-purpurea (" brown-purple "). Fine, hair-like, unbranched, 

 dark-purple filaments, one inch to six inches long. It grows in large 

 patches on rocks and woodwork, floating free, but falling into soft, 

 silky, fleece-like masses when left by the tide. Common on northern 

 shores. (Plate XXXVII.) 



GENUS Porphyra 



("Purple dye") 



This plant, except in color, is like the green alga Ulva. In 

 color it is purple of various shades. The species are named from 

 variations in the outline of the frond. They are found every- 

 where, and throughout the year. The plants are edible, being 

 the laver of commerce, eaten principally by the Chinese, who 

 make them into soup. 



P. vulgaris. Frond a broad, thin membrane of purple color, three 

 to twelve inches across ; margin much waved ; sometimes attached at 

 the center, often widely expanded and folded, sometimes deeply lobed. 

 (Plate XXXVII.) 



P. laciniata. Differs from P. vulgaris in being divided into narrow 

 segments or into wavy, ribbon-like forms. (Plate XXXVII.) 



