account is too brief to form a decided opinion upon. Never 

 having seen a specimen of Mr. Dillwyn's plant, I am not even 

 sure of his synonym, though the magnified portion of his figure 

 is sufficiently like the specimen 1 have drawn from. Still, his 

 saying that the plant is " from three to five inches long," a size 

 greatly above that of my specimen, throws a doubt on the re- 

 ference. 



As a species, 8. fusca (or what I take for it) will rank next 

 8. cirrhosa, from which it differs by its irregular branching, by 

 the remarkable cruciform scattered ramuli, and something in 

 colour and in the length of the joints. 8, cirrhosa is parasitical 

 on other Algae ; but too little is yet known of the history of 8. 

 fusca to say that it is not so. No foreign author appears to be 

 acquainted with the plant; Agardh having adopted it on the 

 authority of Dillwyn's figure. 



Fig. 1. Sphacelaria fusca: a tuft: — of the natural size. 2. A filament. 3. 

 Portion of the same, with one of the three-forked ramuli : — both magnified. 



