. RHODOMELACEiE. 105 



abundant in this than in any other species except P. 

 fibrillosa, and, taken in conjunction with other characters, 

 afford the best means of determining its identity. In 

 some specimens these fibres are the seat of oblong yellow 

 bodies, called antheridia. 



Polysiphonia pulvinata. Cushioned Polysiphonia. 



Fronds spreading over rocks in dense roundish tufts about 

 an inch high; branches springing at right angles from the 

 creeping stem, erect, forked, flaccid, very slender ; branch- 

 lets short, scattered, spreading, sometimes curved ; articu- 

 lations, in the main branches, about three times as long as 

 broad, in the branchlets, about half the length of their 

 breadth. Spores in comparatively large, narrow-mouthed, 

 urn-shaped, stalked conceptacles ; tetraspores in single rows, 

 in the branchlets. 



With the exception of P. obscura, this is the smallest 

 of our native Polysiphonue. It is annual and grows on 

 rocks between the tide-marks, in moderate abundance 

 in many localities. Its small size, creeping habit, and 

 general appearance render it an easy species to deter- 

 mine. 



Polysiphonia Griffithsiana. Mrs. Griffiths's 

 Polysiphonia. 



Fronds about four inches long ; stem simple ; branches 

 alternate, spreading, those nearest the base longer than 

 those next above them, and thus decreasing gradually as 

 they approach the apex of the. frond; branchlets dichoto- 

 mous, flaccid, slender ; tubes, four primary and four se- 

 condary ; articulations about once and a half as long as 

 broad. Spores in ovate, stalkless conceptacles. 



