ECTOCARPACE^. 77 



Sphacelaria filicina. Fern-like Sphacelaria. 



Frond shaggy at the base, slender, irregularly branched, 

 from an inch to four inches high. Spores solitary, formed 

 in the axils of the branchlets. 



When growing on rocks, etc., in shallow water, this 

 species is more robust and rigid than when parasitic on 

 algse at greater depths. In the 'Phycologia Britannica' 

 the latter form is described and figured as a distinct 

 species under the name S. sertularia ; but Dr. Harvey 

 evidently leans to the opinion that it is only a variety, 

 and instances several analogous variations in other species. 

 Subsequent writers have confirmed this opinion, which I 

 am the more ready to adopt as the species of this genus 

 are very prone to put on different appearances, and are 

 in consequence very puzzling to young collectors. 



Sphacelaria scoparia. Broom-like Sphacelaria. 



Frond coarse, very rigid, from two to four inches high, of 

 a dark-brown colour, the lower part of the stem covered 

 with woolly fibres. Spores in bunches in the axils of the 

 branchlets. 



This species has also two distinct states dependent on 

 the season of the year. In summer it is robust and 

 rigid, and its stems are densely set with tufts of branch- 

 lets. In winter it becomes slender and delicate, and 

 only single branchlets occupy the places of the tufts. 

 There are, however, intermediate forms, which indubit- 

 ably connect these two extremes. 



Sphacelaria plumosa. Feathery Sphacelaria. 



Frond naked at the base, irregularly branched, from two 



