OCHLOCH^TE. — ULVACEJi. 211 



Sab-order 2. Ch^tophor^. 



IV. OcHLOCHiETE. Thw. [Plate 25, E.] 



Frond disciform, appressed. Filaments cylindrical, radi- 

 ating from a central point, irregularly branched, consisting 

 of a single series of cells, each of which is most commonly 

 produced above into a rigid inarticulate seta. EndocJirome 

 green. Fruclijicaiion unknown. Thw. — Name, from ox>'0(;, a 

 miiltitnde, and %aiT)i, a bristle. 



1. O. hystrix, Thw. in Harv. Phyc. Brit. t. ccxxvi. 



On stems, &c. in a lake of brackisli water called " The little sea,'' near 

 Wavebani, Dorset, Rev. W. Smith ; also in fresh water ditches near Bris- 

 tol, G. H. K. Thivaites. Forming a Tninute dot-like disk, on the leaves 

 of grasses, <.Si:c. — Filaments closely appressed to the substance on which 

 they grow, radiating from a central point, irregularly divided, and fre- 

 quently cohering laterally. Cells oblong, each usually furnished with a 

 tubular, very long, diaphanous bristle. 



Order XVI. ULVACE.E. 



Grev. Alg. Brit. p. 168 ; Hook. Br. Fl. ii. p. 309 ; Harv. 

 in Mack. Ft. Hib. part iii. p. 240 (in part) ; J. Ag. Alg. 

 Medit. p. 14; Endl. Sd Siippl. p. 18. 



Diagnosis. — Green or purple, marine or fresh water Algae, 

 composed of small polygonal cells, forming expanded mem- 

 branes, or membranous tubes ; very rarely arranged in fila- 

 ments. 



Natural Character. — Root a small disk. Frond in all 

 the genuine plants of the order membranaceous, composed of 

 minute, polygonal, and commonly flattened cellules coher- 

 ing in filmy strata, and connected into laminae by means 

 of firm gelatine. The surface of the membrane is usually 

 areolated, and in some cases beautifully tessellated, the cells 

 being arranged in parcels of four and multiples of that num- 

 ber, forming regular patterns, like mosaic pavement. These 

 membranous fronds are frequently expanded, in which case 

 they seldom assume a definite figiue, generally being of very 

 uncertain form in different individuals of the same species, 

 and being frequently much lacerated during growth. Some- 



p2 



