58 RHODOMELACE^. v. 



divisions three or four. A cross section of the stem shows seven or eight cells sur- 

 rounding a central cavity. Conceptacles borne on the ends of shortened branches. 

 I have not seen stichidia. Colour a dull brownish purple. Substance rigid. It 

 does not adhere to paper in drying. 



This plant is abundant in estuaries of rivers in Carolina and Florida, and pro- 

 bably in other Southern States. The only other specimens I have seen were given 

 me by Capt. Pike of Brooklyn, having been collected by him in July, 1848, at the 

 Isle of Shoals (lat. 43°); and by Mr. Hooper, collected at the estuary of the Hudson. 

 I have not heard under what circumstances Capt. Pike's plant grew, whether in 

 open sea or estuary. There is no appreciable difference in ramification between it 

 and the Carolinian specimens. 



Plate XIV. D. Fig. 1. Bostrtchia rivularis, growing on a piece of wood ; the 

 natural size. Fig. 2, two erect stems, rising from a creeping filament ; fig. 3, pinna 

 and portion of a stem ; fig. 4, cross section of the stem ; fig. 5, conceptacle ; all 

 magnified. 



4. BosTRYCHiA Tuomeyi ; frond capillary (small), irregularly divided ; branches 

 erecto-patent, not much branched, articulato-tessellate, four-tubed and subquadran- 

 gular, rough with broken ramuli below, densely clothed with very slender, inflexed, 

 alternately branched, single tubed ramuli above ; cells of the ramuli once and half 

 to twice as long as broad. (Tab. XIV. E.) 



Hab. On rocks. Pine Islands, Florida, Prof. Tuomey. (10). (v. s. in Herb. T. C. D.) 



Fronds tufted, about inch and half high, capillary, irregularly divided into 

 numerous, erecto-patent, simple or forked branches. Lower part of the stem and 

 branches naked, or beset with the spine-like remains of broken ramuli ; the upper 

 and younger parts densely clothed with inflexed, very slender, slightly branched 

 ramuli. The stem and branches are tetrasiphonous, four large coloured cells sur- 

 rounding a central cell ; and when viewed laterally appear articulate, the internodes 

 shorter than their breadth and marked with three tubes. The raimdi are formed 

 of a single string of cells. Colour a dark lurid purple. Substance rather soft. In 

 drying, it adheres pretty firmly to paper. 



I have seen no fructification, and the generic relations are therefore at present 

 doubtful, the structure of the frond being that of a Polysiphonia -with very short 

 internodes. Still it seems to me to range naturally in the present group, from the 

 other species of which it chiefly differs in having very few (four) cells in the peri- 

 pheric stratum. The ramuli are of precisely the same structure as those of B. 

 calamistrata, and the colour is that blackish purple so cliaracteristic of this genus. 



I bestow the specific name in compliment to Prof Tuomey, of the University of 

 Alabama, to whom I am indebted for an interesting collection of Floridan Alga?. 



Tab. XIV. E. Fig. 1, Bostrychia Tuomeyi ; the natural size. Fig. 2, apex of a 

 branch ; fig. 3, small portion of a branch, to show the cellular structure ; fig- 4, 

 cross section of the same ; fig. 5, a ramellus ; fi.g. 6, small portion of the same ; all 

 more or less highly magnified. 



