Seh. GONGYLOSFERME^. ( 119 ) Fam. CERAMIACE.E. 



Plate CIX. 

 CROUANIA ATTENUATA.— oT. Ag. 



Gen. Char. — Frond gelatinous, cylindrical, moniliform, consisting of a single-jointed 

 tube, emitting at the joints dense whorls of short dichotomously multifid ramuli. 

 Fructification of two kinds, on distinct plants: 1. "Favellidia, suLsolitary near 

 the apex of the rarauli, affixed to the base of the whorled ramelli, and covered by 

 them, containing, within a hyaline membranous perispore, a subglobose mass of 

 minute spores ; " 2. Obovate tetraspores, produced near the base of the ramuli. 

 Name in honour of the brothers Crouan of Brest, 



Crouania attenuata.—J. Ag. Alrj. Medit. p. 83 ; Endl. 3rd Suppl. p. 36 ; 

 Harv. P. B. plate 106 ; Harv. Man. p. 155 ; Earv. Si/)), p. 128 ; 

 Atlas, plate 50, fig. 229 ; Harv. N. B. A. part 2, p. 226; J. G. Agardh, 

 Sp. Gen. Alg. vol. ii. p. 105. 



Mesogloia attenuata. — Ag. Syst. p. 51, 



Mesogloia moniliformis. — Griff, in Wyatt, Alg. Danm. No. 197 ; Harv. Man. 

 1st ed. p. 49, 



G-RiFFiTHSiA nodulosa. — Ag. Sp. Alg. vol. ii, p, 136. 



Callithamnion noduloswn. — Kiitz. Phyc. Gen. p. 373. 



Batrachospermum attenuatum. — Bonnem. 



Hab. — Parasitical on the smaller Algje, particularly CladostepJius spongiosus. Annual. 

 Summer, Very rare. Salcombe Bay {M)-s. Wyatt) ; Mousehole near Penzance {Mr. 

 Ralfs) ; Plymouth {Dr. Cocks). 



Geogr, Dist. — Mediterranean and Adriatic Seas; Atlantic coasts of France. Very 

 rare, as above. 



Description, — Eoot, a minute disc. Fronds tufted, parasitical, from 

 half an inch to one and a-half or two inches in length, much branched 

 in an alternately pinnated manner ; branches distant, cylindrical, and 

 moniliform, attenuated at the points, erect or erecto-patent. Structure 

 composed of a single cylindrical, articulated filament, the joints cylin- 

 drical, three to four times longer than broad near the base, gradually 

 shorter upwards, emitting at each joint a dense whorl of multifid ramuli, 

 the divisions of which are short, fastigiate, articulated, trichotomous at 

 the base, dichotomous upwards at each joint. Substance gelatinous, and 

 closely adhering to the paper in drying. Favellidia seem to be rare on 

 British specimens, and we have never seen them. Tetraspores are com- 

 mon, and are produced near the base of the ramuli by the metamor- 

 phosis of one of the divisions, and are sessile, obovate, and triparted. 



