Ser. Melanosperme^e. Fam. Ectocarpea. 



Plate CCCXLIX. 



SPHACELARIA RACEMOSA, Grev. 



Gen. Char. Filaments jointed, rigid, distichously branched, pinnated; 

 rarely simple or subdichotomons. Apices of the branches distended, 

 membranous, containing a dark, granular mass. Fructification, ellip- 

 tical utricles (or spores), borne on the ramuli. Sphacelaria (Lyngb.), 

 — from <xcj)aKe\os, gangrene, alluding to the withered tips of the 

 branches. 



Sphacelaria racemosa ; " an inch in height, tufted, olivaceous, somewhat 

 rigid, the fronds dichotomous; articulations equal in length and 

 breadth; capsules oval, racemose, pedunculate." Grev. 



Sphacelaria racemosa, Grev. Scot. Crypt. Ft. vol. ii. t. 96. Grev. Fl. Ed in. 

 p. 314. Harv. in Hook. Br. FL vol. ii. p. 325. Harv. Man. ed. 1. p. 39. 

 ed. 2. p. 57. /. Ag. Sp. Alg. vol. i. p. 31. Kiitz. Sp. Alg. p. 4G6. 



Hab. In tide-pools ? Very rare. Frith of Forth, opposite to Caroline 

 Park, Sir John Richardson. 



Geogr. Distr. Only found in the above locality, and there only once (about the 

 year 1821). 



Descr. " Plant tufted, about'an inch in height, of an olive-green or olive-brown 

 colour. Frond filiform, somewhat rigid, 3-4 times dichotomous, the dicho- 

 tomies acute. Articulations equal in length and breadth, diaphanous to the 

 base. Summits of the branches not sphacelated in my specimens, but 

 somewhat dilated and hyaline, as in many other species previous to the spha- 

 celation making its appearance. Fructification, oval capsules, surrounded 

 by a very narrow pellucid border, pedicellate, and arranged in a racemose 

 maimer, on a common jointed peduncle. Racemes suberect, arising from 

 various parts of the frond." — Grev. Scot. Crypt. I. c. 



In this species we have the remarkable fact, occasionally nut 

 with in all departments of natural history, of a species distin- 

 guished by strongly marked characters having been seen but oner, 

 and that in very small quantity. The tuft from which Dr. Gre- 

 ville's figure, and the above description, which I have transferred 

 from his work, were taken, has also served me in making the 

 drawing for the plate now given, having been kindly placed in 

 my hands for that purpose by Or. Greville, with the' liberal per- 



VOL. 111. 2 I 



