66 MARINE ALG^E 



waved on margin; substance soft and thin; dotted with spores. In the 

 young plants fine hairs emerge from the dots, but disappear later, and 

 the fronds become darker and more rigid. Found in summer on rocks 

 and on other algae on the Long Island and New England coasts. 



P. tenuissima. Fronds smaller and more slender than in P. latifolia; 

 thin and delicate. Found on eel-grass and Chorda filum. 



P. plantaginea. Fronds dark brown, leathery, leaf -like, blunt or 

 wedge-shaped on top; dense clusters of hairs on the dots; six to twelve 

 inches long, one inch to one and a half inches wide. 



GENUS Asperococcus 



This genus differs from Punctaria in having a tubular instead 

 of a flat frond. (Plate IX.) 



A. eehinatus. Resembles Enteromorpha in being tubular ; compressed 

 or inflated ; obtuse at the apex ; attenuated at the base. It differs from 

 Enteromorpha in being olive in color, and in being covered with small 

 oblong dots of darker shade. When the plant is young the dots are 

 hairy. It grows in clusters, two to eighteen inches long, one half of an inch 

 to one inch wide. Common along the New England coast. 



GENUS Phyllitis 



P. fascia. Fronds light olive-green, leaf -like, three to six inches long, 

 one fourth to one half of an inch wide ; margin entire, slightly waved ; 

 contracted at base to short stalk ; attached by disk. This species grows 

 in bunches on rocks and stones at low- water mark, and is very common 

 everywhere. (Plate X.) 



ORDER DESMARESTIACEJE 



(Named for M. Desmarest, a French naturalist) 



GENUS Desmarestia 



D. mridis. Filaments cylindrical, about as thick as a bristle ; branches 

 opposite, in pairs, at intervals on the main stem. The branches branch 

 again and continue to be disposed in the same manner. All are long and 

 ultimately become very fine. The color is olive-green, becoming verdi- 

 gris-green when exposed to the air for a short time or placed in fresh 

 water. The species grows in deep tide-pools and below low- water mark, 

 forming fine, feathery plumes, often a yard long, which give submerged 

 rocks the appearance of a luxuriant garden. (Plate X.) 



D. aculeata ("spiny"). Fronds cylindrical at base, flattened above; 

 branches long and straight, arranged alternately, when young beset with 

 pencils of fine hairs, often one half of an inch long, which, later, fall off, 

 leaving alternate spines along the edges of the flattened branches. It 



