Ser, RHODOSPERMEyE. Fam. S^harococcoiclea. 



Plate CLXX. 



DELESSERIA REVOLUTA, Harv. 



Gen. Char. Frond leaf-like, membranous, areolated, symmetrical, simple 

 or branched, midribbed. Fructification : 1, hemispherical concep- 

 tacles, sessile on the midrib or on a lateral nerve, containing a tuft of 

 moniliform spore-threads on a basal placenta ; 2, tripartite tetraspores, 

 in definite sori or spots, on the frond or on accessory leaflets. — 

 Delesseria [Ag.), in honour of Baron Delessert, a distinguished 

 patron of botany. 



Frons foUacea, memhranacea, areolata, symmetrica, simplex v. ramosa, costata. 

 Fruct. : 1, coccidia in costd venisque froudis sessilia, hemispJirjerica, fila spuri- 

 fera moniliformia a placenta hasali emissa foventia ; 2, tetrasporce triangule 

 divisee, in soros dejinitos collectce. 



Delesseria revolnta ; frond dichotoraous, formed of a string of snaall, 

 strongly ribbed, epiphyllous leaflets, with revolute apices ; leaflets 

 ovato-lanceolate, serrate, wavy, delicately membranous, pale-red, once 

 and a half to twice as long as their breadth ; sori unknown. 



D. revoluta; fronde dichotoma e folioUs parvis costatis seriatim epipJiyllis apice 

 revolutis formata ; foUolis ovato-lanceolatis serratis undulatis tenui-mernbra^ 

 naceis latitudine sesqui- v. siibduplo-lougioribus ; soris ? 



Delesseria revoluta, Earn. inTrans. R. 1. Acad. v. 22. p. 548 ; Alg. Austr. 

 Exsic. ii. 279. 



Hab. Parasitical on Algse. King George's Sound, and Eottnest Island, 

 W.H.H. Eremantle, G. Clifton. 



Geogr. Distr. West and south-west coasts of Australia. 



Descr. Root a minute disc. Full-grown frond 4-5 inches long, dichotomously 

 branched, with a strong midrib, 2-2|- hues wide, divided into short, joint- 

 like internodes, something after the maimer of an epiphyllous Cactus. This 

 frond is formed by a series of small leaflets, growing one from another, each 

 from i to i inch long, strongly ribbed, sharply serrated, and revolute at the 

 point. The new leaflet successively springs from the midrib of the previous 

 one, on the dorsal surface, at about \ of the length of the leaflet below its 

 apex ; sometimes one, sometimes two spring from the same point. The 

 structure is delicate and thin, but the cells of which it is composed are small, 

 ranged in lines obUquely from the midrib to the margin. The fruit has not 

 yet been observed. The colour is a pale rose-red, soon discharged in fresh- 

 water. The stibstance is soft and membranous, and in drying the frond 

 adheres closely to paper. 



No fructification has yet been noticed on this plant, and con- 



