SIPHONACE^. 243 



deep-water habitats, and I have several times found fair- 

 sized specimens growing in shaded situations in pools 

 near the very highest limit of the tide. I may add that 

 its appearance in the water is similar to that of rounded 

 pebbles, so that it may be easily overlooked, unless the 

 sense of touch be used to aid the eye. 



Codium tomentosum. The tomentose Codium. 



Fronds growing several together or rarely singly, cylin- 

 drical orflattened, erect, I'orkedly branched, from a few inches 

 to a foot or more long, and from a quarter to three-eighths 

 of an inch in diameter, composed of an axis of numerous 

 interwoven, slender fibres, from which issue horizontal, club- 

 shaped filaments, whose tips constitute the surface of the 

 frond. Zoospores in somewhat oval, nearly stalkless 

 sporangia on the sides of the club-shaped filaments. 



This plant is not only the most widely distributed 

 species of the genus, but also rivals, in this respect, 

 almost any other sea-weed : from the equator to either 

 pole, and in both hemispheres it is abundant on nearly 

 every coast. No less distinct than it is common, it may 

 be readily recognized by its thick, sponge-like, dark- 

 green branches, clothed with short, soft hairs, which, 

 when spread out in water, give the plant a cotton-like 

 appearance, whence it derives its name of tomentosum. 

 It grows on rocks in pools, which are sufficiently deep 

 to prevent the possibility of its being exposed to the air 

 when the tide is down. It is perennial, and attains its 

 most luxuriant growth in summer. 



Codium amphibium. The amphibious Codium. 



Eronds rising from an indefinite, spreading layer of en- 



r2 



