V. RHODOMELACE.E. 47 



broad in the ramuli, and once and half to twice their breadth in the branches. 

 Conceptacles ovato-urceolate, acuminate, or produced at the orifice into a long beak, 

 borne on peduncles longer than themselves, often twice as long, originating on the 

 principal branches of the frond, and more than twice the diameter of the ordinary 

 rarauli. Tetraspores immersed in the ramuli. Colour a brown red of variable inten- 

 sity ; in old specimens the branches are sometimes colourless while the ramuli are 

 strongly coloured. Substance soft. It adheres, but not very strongly, to paper in 

 drying. 



The smaller and less branching specimens resemble P. obscura, but are much 

 more delicate ; the larger are quite unlike any other North American species. 

 Since our figure was prepared I have received from Dr. Blodgett specimens bearing 

 conceptacles. These are very curious, shaped like those of Dasya elegans^ and 

 borne on still longer peduncles. 



Plate XVI. C. Fig. 1. Polysiphonia Pecten Veneris ; the natural size. Fig. 2. 

 part of a branch magnified ; fig. 3. ramulus, with tetraspores, more highly magnified. 

 D. Figs. 1 and 2, var. ^. the natural size. Fig. 3, part of a branch ; fig. 4, small 

 piece of the same and ramulus with tetra'spores ; fig. 5, cross section of a branch ; 

 the latter figures more or less magnified. 



21. PoLTSiPHONiA exiUs ; filaments densely tufted, creeping, afterwards ascending 

 or suberect, furnished with a few distant, secund, unequal, filiform ramuli ; inter- 

 nodes shorter than their breadth in all parts of the frond ; tubes nine ; tetraspores 

 in the ramuli. 



Hab. Key West, W. H. H. (24) Br. Blodgdl, (v. v.) 



Densely tufted. Filaments matted together at base and there attached by lateral 

 rooting fibres ; afterwards ascending or sub-erect, about an inch in length or rather 

 more, ultra-capillary, generally simple, furnished at short intervals with numerous 

 very unequal, secund ramuli, long and short often indiscriminately ranked together, 

 the ends of the filaments generally bare. Internodes very short, about half as long 

 as broad, with pellucid dissepiments. A cross section shows nine tubes. Tetra- 

 spores in distorted ramuli. I have not seen conceptacles. Colour a dark brown 

 red, becoming much browner in drying. Substance coarse and rather rigid. It 

 imperfectly adheres to paper in drying. 



Allied to P. obscura, Ag. ; Init more robust, and yet with fewer and broader 

 tubes. I also collected at Key West one or two specimens of a Polysiphonia nearly 

 allied to this, diflfering in being less robust, less branching, having longer inter- 

 nodes and a rather brighter colour. As the specimens are not in a very good state, 

 I am unwilling to give them a name at present, and thereby add to the sufficiently 

 numerous list of bad species in this genus. 



