80 COMMON SEAWEEDS. 



Polysiphonia Subtjlifeea. — Very local, but to be 

 found on the rocks in deep water at "Weymouth, and 

 sometimes in the Channel Islands, higher up, parasitic 

 on seaweed RytipMcea and Poly ides. 



Polysiphonea Purcellata. — This is very rarely 

 found actually growing, but comes up in dredging, or 

 is thrown ashore after a storm. 



Poltsiphonia Beodkei. — A large, somewhat coarse 

 species, of brown colour, which speedily decomposes 

 and emits a disagreeable smell in fresh water. The 

 opaque stem, concealing its seven siphons, which can 

 only be discovered by a transverse section, and the 

 pencil-like tufts of delicate fibres are the chiefs marks 

 by which to distinguish it. We find it commonly on 

 the coasts round England, Scotland, and in the Chan- 

 nel Islands, 



PoLYSIPHOSTA AlTINIS and POLTSIPHONIA SlIB- 



tjlieeea are also found in lowest-tide pools, but are 

 not remarkable for beauty, and do not belong to the 

 common objects for a seaweed book. 



CALLITHAMNIOK 



(Name signifying " a beautiful shrub or plant.") 



This family contains the smallest yet loveliest of 

 the seaweeds : some of them attain to a length of eight 

 inches, and in appearance so much resemble JPolysi- 

 plionia as to require the aid of a pocket lens or micro- 



