or less brown ; when young greenish. /3. differs in being much more slender, 

 and generally is a parasite on other small Algae. 



A very common, but we cannot say a very beautiful plant ; 

 one of the least highly organized of the family to which it 

 belongs, and the coarsest in its mode of growth. The only 

 variation to which it is subject is the size, and the more or less 

 tapering extremities. The size varies so greatly that very good 

 observers have contended for two species, the smaller one of 

 which we retain as a variety, although it passes so insensibly into 

 the larger form that no distinct limits can be assigned between 

 them. From A. Turneri (PL XL) this is at once distinguished 

 by the thicker substance, darker colour, tapering base, and by 

 being only moderately inflated. The former species is also re- 

 markable for the bluntness of its frond. The present more nearly 

 resembles A. compresszis, (PL LXXIL), some ill-coloured and 

 narrow examples of which have very much the outline and general 

 aspect of A. ec/iinafus, and can scarcely be known from it except 

 by the character of compression : a character whose distinctness 

 is greatly lost in the dry state. 



Other specimens frequently are met with which resemble 

 Chorda lomentaria, even to the extent of being here and there 

 constricted. The fructification affords the best mark of dis- 

 tinction from puzzling forms of the latter. 



Fig. I. Asperococcus echinatus ; fronds: — of the natural size. 2. Portion 

 of the tube, with sori : — magnified. 3. Section of the membrane and sorus : 

 — highly magnified. 



