36 RHODOMELACE.E. • v. 



them, which occasionally have one or two short ramuli. I have not seen greater 

 composition. Internodes very short in the prostrate filaments, about once and half 

 as long as broad in the erect branches, appearing three tubed on the latter view, 

 and found by cross section to be square, composed of four large tubes surrounding 

 a rhomboid cavity. Colour a dull, dark reddish brown. Substance rather rigid. 

 It does not adhere firmly to paper in drying. 



This species sometimes intertwines so densely among the ramelli of Digmia as 

 to form with them a dense entangled mat, in which other parasites then take root. 

 I have also seen it at Key West on Lauvencice. Montague's Cuban specimens grew 

 on Sargassum. 



6. PoLYSiPHONiA breviarticulata, Ag. tufts dense ; filaments rather rigid, tetra- 

 gonal, rising from a mat of creeping fibres, erect (3-5 inches long), as thick as hog's 

 bristle, not much branched ; main stem simple, or once or twice forked, somewhat 

 naked below, beset above with numerous virgate, very erect primary branches, set 

 at intervals with several very slender secondary branches, which are naked below 

 and alternately multifid above ; internodes uniformly shorter than their diameter 

 in all parts of the frond, swollen at the nodes ; conceptacles ovate, sessile ; tetra- 

 spores in distorted terminal ramuli. Ag. Sp. Alg. 2, p. 92. Kutz. Sp. p. 815. 

 P. physarthra, Kg. I. c, 815. (Tab. XVI. B.) 



Hab. Abundant on maritime rocks, near highwater mark, at Key "West, W. H. H. 

 (No. 19), Dr. Blodgett (No. 57), Br. Wurdeman (No. 15 and 16.) Vera Cruz, 

 Liebman ! (v. v.) 



Tufts 3-6 inches high, dense. Filaments as thick as hog's bristle, sometimes 

 nearly unbranched, sometimes thrice or four times parted subdichotomously, bare 

 of branches and ramuli below, more or less furnished with alternate branches 

 above. Branches but little divided, long; and virgate, erect, furnished with several 

 slender secondary branches, of greatly less diameter than the part they spring from. 

 These are simple and naked in their lower half, and alternately multifid above. 

 Apices abundantly fibrilliferous when young. Art'mdations in all parts of the 

 fi'ond much shorter than their diameter, visible to tlie naked eye and then appear- 

 ing with opaque nodes ; under the microscope pellucid, with very wide quadrate 

 tubes and transparent interspaces. A cross section of the stem is square, with 

 four wide tubes surrounding a small central cavity. ConcqMcles ovate, sessile on 

 the sides of the multifid ultimate ramuli, which on fertile specimens are shorter and 

 more closely branched. Tetraspores in the tips of the ramuli. Colour a dull red- 

 dish brown. Substance rigid, not closely adhering to paper. 



The Key West specimens agree with one from Vera Cruz mentioned above, but 

 are rather more robust than the Mediterranean form, and more furnished with 

 lateral ramuli. I had at first thought them difierent, and may perhaps have 

 distributed a few specimens under the MS. name P. littoralls, which I gave at Key 

 West to this plant, from its profuse abundance along the shore, near high water 



