Sku. GONGYLOSPERME/E. (117) Eam. CEKAMIACEvE. 



DUDRESNAIA COCCmEA.—Bonncm. 



Gen. Char. — Frond very tender and gelatinous, composed of two strata of filaments 

 forming a cvliiulrical frond ; axis consisting of one or more longitudinal articulated 

 filaments, producing at their joints whorls of dichotomously multifid vertical 

 ramuli. Fructification of two kinds, on distinct plants : 1. Favellidia, produced 

 at the base of the ramuli ; 2. Tetraspores, transversely quadripartite, terminal at 

 their apices. Name in honour of M. Dudresnay. 



DuDRESXAiA coccinea. — Frond filiform, very flaccid, much branched ; 

 branches irregular, somewhat alternate, patent or erecto-patent ; whorls 

 of ramuli at first moniliform, at length approximate. 



DuDRESNAiA coccinea. — Bonnem. in Journ. Phys. vol. xciv. p. 180; Crouan, Nouv. 

 An. Sc. Nat. vol. iii. p. 98, t. 2, f. 3—4 ; /. Ag. Alrj. Medit. p. 84 ; 

 Endl. 3rd Suppl. p. 37 ; Ilarv. P. B. plate 244 ; Harv. Man. p. 154 ; 

 Harv. Syn. p. 127 ; Atlas, plate 49, fig. 220 ; /. G. Arjardh, Sp. 

 Gen. Alg. vol. ii. p. 108. 



Mesogloia coccinea. — Ag. Syst. p. 51 ; Hoolc. Bi\ Fl. vol. ii. p. 386 ; Wyatt, Alg. 

 Damn. No. 148 ; Harv. in Made. Fl. Hib. part 3, p. 186 ; Uarv, 

 Man. 1st ed. p. 48, 

 RivuLARiA verticillata. — E. Bot. t. 2466. 

 Hab. — On rocks, &c., near low-water mark ; and in three to twelve fathoms water. 

 Annual. Summer. Very rare. Brighton {Mr. Borrer) ; Sidmouth and Torquay {Mrs. 

 Griffiths and Miss Cutler) ; Salcombe {Mrs. Wyatt) ; Plymouth {Rev. W. S. Ilore) ; 

 Falmouth {Miss Warren) ; Jersey {Misses White and Turner) ; Bantry Bay {Mise 

 Hutchins) ; An-an {Mr. D. Landshorough) ; near Dunbar {Mrs. R. M. Stark). 

 Geoqr. Dist. — Atlantic coasts of France. 



Description. — Root, a minute conical disc. Frond attenuated at the 

 base, filiform, four to six or " ten " inches long, about a line in thickness 

 — including the whorls, — much branched from near the base ; branches 

 irregular,mostly alternate, upper ones very short, patent or erecto-patent ; 

 the axils rounded, the apices obtuse. Structure : when young composed 

 of a simple, articulated, longitudinal filament, emitting at the joints 

 dense whorls of short, vertical, dichotomously multifid ramuli ; at length, 

 by the superposition of other filaments of a similar structure, each with 

 its whorl of ramuli, the whorls become so close as to form a close 

 stratum of vertical filaments, constituting the periphery of the frond. 

 Substance very soft and gelatinous, soon decomposing, adhering tenaci- 

 ously to paper in drying. Colom-, a brilliant crimson when fresh, reddish 

 brown when diy, dirty white in decay, Favellidia formed at the base 

 of the vertical ramuli. Tetraspores oblong, terminal at their apices. 



This interesting plant is one of the rarest as well as the most beautiful 

 of our native Algae. An inhabitant of deep water, it is never met with 



