MARINE ALGJE 



GENUS Mesoglcea 



M. virescens. Soft, slimy filaments, with branches and branchlets ; 

 olive-greeno (Plate XL) 



M. divaricate,. Fronds two to twenty-four inches high ; branching 

 irregularly, and generally without definite main axis ; branches flexuous, 

 solid at first, later hollow ; branchlets short and wide-spreading. Com- 

 mon from Cape Cod southward: abundant in Long Island Sound. 

 (Plate XI.) 



GENUS Leathesia 



This singular alga resembles a tuber and cannot be mistaken 

 for any other plant. Its fronds are gelatinous, fleshy balls, one 

 half of an inch to two inches in diameter, at first solid, afterward 

 lobed and hollow. It grows singly or in bunches on algae and on 

 sand-covered rocks, and is found in summer on every coast. The 

 common species is known as L. difformis or L. tiiberiformis. 



GENUS Myrionema 



Minute algae which grow on other plants and which appear 

 like dark spots, or, at first, like stains, on Ulva, Enter omorpha, and 

 small red algae. These spots, which to the naked eye appear 

 like decay, show, under the microscope, a jelly-like substance 

 full of beaded filaments. 



ORDER LAMINARIACEJE 



The plants of this order have large and coarse fronds (some 

 attaining an immense size), with stems, branching root-like hold- 

 fasts, and expanded leaf-like laminae. They are leather-like, not 

 articulated, olive-green or brown in color, and sometimes yellow 

 and semi-transparent. They grow in deep water and are found 

 washed ashore. Sometimes small plants are found in deep tide- 

 pools at low-water mark. Some species are perennial. In these 

 instances the stems only survive, and the laminae are repro- 

 duced annually. The new growth takes place at the apex of the 

 stem. The old lamina is pushed off, but is held on the summit 

 of the new growth until the latter has matured. 



In the genus Chorda the fronds are cylindrical; in Agarum 



