Catenella.] ALG7E I NARTICULAT7E. 309 



Ag. Sp. Alg. v. \. p. 214. — Gastridium filiforme, Lyngb. — Viva 

 purpurascens, E. Bot. t. 641. — Ulva incrassata, U. sponyi- 

 formis, and U.JUiformis, Ft. Dan. — ;3. crispata ; frond com- 

 pressed waved curled and twisted, of a brownish-purple colour. 

 Grev. I. c. — Holy menia purpurascens, var. crispata, Grev. Crypt. 

 Fl. t. 240. 



On rocks and stones in the sea, frequent. — /3. Firth of Forth, Dr. 

 Greville. Firth of Clyde, at Helensburgh. 0. Summer. 



45. Catenella. Grev. Catenella. 



Fronds filiform, somewhat compressed, creeping, throwing 

 up numerous branches, contracted, as if jointed, in a moniliform 

 manner, composed interiorly of branched filaments radiating from 

 the centre. .Fructification unknown. Grev. Alg. Brit. p. 167. 

 t.\7. — Name; catenella, a little chain, which its fronds resem- 

 ble. — In deference to Dr. Greville, I adopt this Genus ; but its 

 fructification is wholly unknown. Mr. Harvey, too, observes 

 in a letter to me, " I confess I would rather leave this plant in 

 Chondria (Gastridium, Grev.) until the fructification be dis- 

 covered, as it perfectly agrees with the other species in habit, 

 and, unless I greatly err, in structure also. When at the coast 

 I took some pains, struck with the similarity in habit between 

 the Gastridia and C. Opuntia, to dissect, as minutely as I was 

 able, the fronds of G. articulation, as being the species most near- 

 ly allied (externally) to the plant in cpiestion ; and the result 

 was a conviction on my part that the structure was precisely 

 similar. I found the pseudo-joints full of very lax gelatine, in 

 which articulated filaments appeared to be loosely floating, fixed 

 only to the periphery, though I presume, originating in a central 

 point ; but my instruments were not sufficiently delicate to dis- 

 sect them without laceration ; neither has Dr. Greville been able 

 to do so with C. Opuntia. The filaments themselves are colour- 

 less, arachnoid, much branched in a dichotomous manner." 



I. C. Opuntia, Grev. (Opuntia- like Catenella). — Grev, Alg. 

 Brit. />. Ki6. t. 17. — Chondria Opuntia. Book. Scot, P. II. 



p. 106. — Halymenia Opuntia, Ag. Sp. Alg. r. 1. j). 217. — 



Gigdrtina Opuntia and pilosa, Lamour Rivularia Opuntia, 



H. Hot. t. 1868.-— Chordaria opuntia. Spring. — Lom entari a 



Opuntia. (iaill. — FuCUt Opuntia. Ootid, and Woodw. — Turn. 

 Si/n. Fur. j,. 307, Hist. FUC. t. 107. — F. cispitosus. Star/di. — 



F, repens, lAghtf. — I Ira articulataj C. Buds. 



Frequent on the rock} ihorea of Great Britain, y. . — From half an 

 inch to an inch or more in length, densely matted, remarkably catenu- 



luted with the coii.-tru ti<>n-. 



Tribe XI. Ulv \< i 



I 'hints found in tin 000, in f'r, sli -watt r OT OH da nip CTOU ml '. Sr.. 



<7 an herbaceous green orjSne purple colour^ efa thin tender stem* 



