Marine Algce of Berwick-on-Tweed. 357 



This species forms purplish, semi-transparent, filmy patches 

 on the fronds of Fastigiaria and other Algse, the dark colour of 

 the host-plant showing through the frond of the Hapalidium and 

 rendering it almost invisible when wet. The horizontally 

 expanded fronds, are small and very thin, at first orbicular, then 

 through many becoming confluent, indefinite in outline. They 

 adhere very closely to the plant on which they are growing, 

 becoming wrinkled as it contracts in drying, but they do not 

 crumble and fall from it as so many of the epiphytic Melobesia 

 do. The tetrasporic conceptacles are numerous, hemispherical 

 and semi-transparent, the dark coloured zonate tetraspores being 

 clearly visible through the thin cell-walls of the conceptacles. 

 To the naked eye the conceptacles look like so many dark specks 

 on the surface of the frond, and when present serve as a guide 

 to the identification of the species. The cellules composing the 

 frond are oblong or ovoid, arranged in simple or dichotomous 

 lines radiating towards the margin of the frond. With us, the 

 plant has in all probability been mistaken for Melobesia mem- 

 branacea or one of the other epiphytic species of that genus, as 

 it is by no means a rare plant. 



MELOBESIA, Aresch. 



Subgenus EUMELOBESIA. 



Melobesia Lefolisii, Rosanoff. 

 Rech., p. 62, pi. i., fig. 1-12. 

 Descr. Melobesia Lefolisii, Farlow, Mar. Alg. New Eng., p. 180. 

 Syn. Melobesia membranacea, Aresch. in /. Agardh's Spec. Alg ; 

 Harv., Phyc. Brit., pi. 3-t7, A (non Lamour.) 

 Melobesia farinosa, Ktz., Spec. Alg., p. 696 ; Le Jol., Liste Alg. 

 Mar. Cherb., p. 150 (non J. Ag., nee Harv.) 

 Hab. On old Zostera leaves. Frequent. Holy Island, Fenham Flats. 



Melobesia membranacea (Esper.) Lamour. 



Polyp. Flexib., p. 315. — Corallina membranacea, Esper., 

 Zooph. Taf. 12, fig. 1-4. 

 Descr. Melobesia membranacea, Rosanoff, Rech., p. 66. 

 Fig. „ „ Rosanoff, I.e. pi. 2, fig. 13-16 et pi. 3, 



fig. 1. 

 Syn. ,, „ Aresch. in J. Ag., Spec. Alg. n., p. 512. 



Hab. On old Zostera leaves and also on Cladophora rupestris, and other 

 Algse. Not uncommon. Holy Island, Berwick Bay. 



