164 BTNOP8I8 OF BRITISH" SEAWEEDS. 



marks, generally near low- water mark ; not left dry at low 



water. Annual? Summer. 

 It is pleasant in such a genua as Cladophora, where the 

 Bpeciee often Beem to run Insensibly into one another, to 

 find one so broadly distinguished from the rest that there 

 can be no mistake about it. The plant here described is 

 just of this character. Cladophora pellucida may at once 

 pe known by its very distinct di-trichotomous branching, 

 and by there being out a single articulation or cell in the 

 space intervening between, each furcation; that is to say, 

 every internode consists of a single cell. There is no other 

 British species in which this takes place regularly, in all 

 parts of the frond. It thus happens that the individual 

 cells, in this species, are of extraordinary length, those of 

 the lower parts of the filament being sometimes more than 

 an inch in length, very frequently three-quarters of an 

 inch. 



292. rectangnilaris {The rectangular Cladophora); filaments 

 setaceous, rigid, forming intricate tufts ; branches opposite, 

 distant, elongated, patent, furnished throughout with short, 

 opposite, horizontal ramuli ; articulations twice or thrice as 

 long as broad, Harv. Bhyc. Brit. pi. 12. (Atlas, PI. LXIII. 

 Fig. 295.) 



Conferva rectangularis, Griff. 



Hab. South of England ; very rare. In the sea, at depths be- 

 yond the influence of the tides. Annual. Summer. 

 A beautiful species, discovered in the year 1832 by Mr. 

 Borrer, washed up on the beach at Torquay, and occa- 

 sionally found, but very rarely, in the same locality by 

 Mrs. Griffiths and Mrs. Wyatt. jN'o species can be more 

 distinct. The very patent, opposite branches, and the in- 

 variably opposite, distichous, horizontal ramuli are its pe- 

 culiar characteristics. It is most nearly related to C. Hut- 

 chinsicE and C. diffusa, of which it has the size, rigidity, 

 and something of the habit. But the opposite ramuli 

 clearly separate it from either. 



293. Macallana (M'Calla's Cladophora) ; filaments setaceous, 

 rigid, full green, very flexuous, loosely bundled together, ex- 

 cessively branched ; branches alternate or rarely opposite, 

 zigzag, very patent ; ramuli short, recurved, simple or pec- 

 tinated, obtuse ; articulations twice or thrice as long as 

 broad ; endoehrome rather dense, JJarv. Phyc. Brit. pi. 84. 

 (Atlas, PL LXIII. Fig. 296.) 



