pear-shaped, succulent ramuli, about a line or rather more in length, irregu- 

 larly inserted, and often fascicled ; the older branches and stems are more 

 or less denuded, and are then opacjue and smooth. The structure of the 

 stem is very dense, the interwoven filaments of the medullary stratum being 

 closely packed, and the cortical layer thick, composed of radiating, slender, 

 densely-set filaments. Coticeptacles sunk in the medullary stratum of the 

 ramuli, surrounding the central axile filament on all sides ; the nucleus 

 formed of mouiliform, excurrent spore-threads ; spoi-es elliptical. Telraspores 

 zonate, lodged in the cortical layer of rather larger and more succulent ra- 

 muli than those that bear conceptacles. Colour dark-red, becoming darker 

 in the herbarium. Substance cartilaginous and tough, enduring exposure 

 and long- immersion in fresh-water. In drying the frond scarcely adheres to 

 paper, except when young. 



I have long been acquainted with this plant, but until now 

 have hesitated to describe it, from feeling uncertainty both as 

 to the proper genus to which it should be referred, and as to 

 whether it was fully organized, or merely some species in a de- 

 nuded condition. Several specimens recently received from Mr. 

 Clifton, some of them bearing cystocarps, and others tetraspores, 

 have at length satisfied me that the present Alga is entitled to 

 specific distinction ; but I am still doubtful whether I ought to 

 refer it to Arescliougia, or perhaps found a new genus upon it. 

 In its characters it comprises, very nearly, the genera Jreschou- 

 gia and Ergthroclonmm, but does not quite agree with either ; 

 but on the whole — looking to the development of its stem and 

 primary branches — appears better associated with the former. 

 Here therefore I place it, though to admit it 1 have been ob- 

 liged to alter the generic character. 



To complete its history it would be desirable to find it in a 

 young state and growing. We are still ignorant of the form of 

 the immature ramuli, or whether, at any period, it bears flat, 

 foiiaceous appendages. 



Fig. 1. Areschougia sedoides, — the natural size. 2. A cross section of 

 the stem. 3. Some ramuli, m situ, containing conceptacles. 4. Segment 

 of a cross section of a conceptacle-bearing ramulus. 5. Spore from the 

 same. 6. Eamuli, bearing tetraspores. 7. Segment of a cross section of 

 one of them. 8. Tetraspores from the same: — the latter figures variously 

 magnified. 



