42 RHODOMELACE.E. v. 



portion of a branch, with ramuli and a conceptacle ; jiij. 6, transverse section of the 

 stem ; all the latter figures more or less highly magnified. 



** Stem and larger brayiehes inarticulate, more or less completely coated with small, 

 irregular cellules. Ramuli articulate. (Sp. 14 — 17-) 



14. PoLYSiPHONiA ramentacea; stem robust, dendroid, inarticulate, internally 

 four-tubed, irregularly much branched ; branches spreading on all sides, alternately 

 divided ; lesser branches rod-like, simple, set throughout with numerous, short, 

 setaceous, spine like, simple or forked, articulate ramuli; internodes of the ramuli 

 shorter than their breadth, marked with two or three quadrate cells ; conceptacles 

 ovate, borne near the tips of the ramuli. (Tab. XVI. A.) 



Hab. On corals, &c. Key West, W. H. H., Dr. Blodgett. (v. v.) 



Boot discoid. Stem solitary, four or five inches high, twice or thrice as thick as 

 hog's bristle, gradually attenuated upwards, soon forking, and afterwards repeatedly 

 divided in an irregularly alternate manner, the whole system of branches forming a 

 tree-like frond. The larger branches spread towards every side, and are furnished 

 with numerous lateral, secondary branches, scattered or crowded, and either simple 

 or having another series of similar branches, all tapering to a tine point. The stem 

 and branches are alike beset, at distances of half a line or less, with slender, simple 

 or forked, bristle-shaped, quadrifarious ramuli, a line or two in length. These 

 ramuli are pellucidly articulate, the articulations exceedingly short, with sub-qua- 

 di'ate tubes. The stem and branches are opaque, tessellated with small irregular 

 cells ; a transverse section showing four primary tubes, with an external coating of 

 greater or less thickness formed of small cells. Conceptacles ovate, small, sessile 

 near the tips of the ramuli. Antheridia ovato-lanceolate, densely tufted at the apices 

 of the ranauli. Colour a dull reddish brown, darkening in drying. Substance carti- 

 laginous, but soft. In drying, it adheres pretty closely to paper. 



Of this apparently rare species, I collected only a solitary specimen during my 

 visit to Key West. It is abundantly unlike any other North American species, but 

 nearly allied to F. fiexella of the Mediterranean. My specimen, however, difl^ers 

 from any that I have seen of P.ficvella; it recovers better after havmg been dried, 

 the articulations of the ramuli are more distinct, and the byssoid fibres far less 

 copious. 



Plate XVI. A. Fig. 1. Polysiphonia ramentacea; the natural size. Fig. 2, apex 

 of a branch; fig. 3, portion of a ramulus; fig. 4, transverse section of a branch; 

 fig. 5, lateral view of a small portion of the same, to show the surfece cells ; the 

 latter figures more or less highly magnified. 



15. Polysiphonia elongata, Grev. ; stems robust, cartilaginous, irregularly 

 branched, decompound, best, especially toward the end of the branches, with slender, 

 closely set, alternately multifid ramuli, which taper to the base and apex ; articu- 



