IV. 



SPOROCHNACE^. 73 



Order II -SPOROCHNACE^. 



Harv. Man. Br. Alg. Ed. 2, p. 21. Sporochnoidece, Grev. Alg. Brit. p. 36. J. Ag. 

 Sp. Alg. vol. l,p. 160. Kiitz. Phyc. Gm. p. 342. Kiltz. Sp. Alg. p. 567- Bndl. 

 3rd. Suppl. p. 28. Chordariece, in part Ag. Syst.j). xxxvi. Sp>orochnidece and part of 

 Dictyotidce, Lindl. Veg. Kingd. p. 22. 



Diagnosis. Olive-coloured, inarticulate seaweeds, whose spores are attached to 

 external, jointed filaments, which are either free or compacted together into knob- 

 like masses. {Plants of mediocre size, soon becoming flaccid in the air, and then chang- 

 ing to a verdigris-green colour). 



Natural Character. Root usually a small, naked disc or point of attachment ; 

 in Carpomitra, bulbous and coated with woolly threads. Fronds of mediocre size, 

 and much branched, frequently bushy, having, whilst living, a clear and rather 

 brio-ht brownish olive or chestnut colour, and a cartilaginous, firm, crisp substance ; 

 but rapidly becoming flaccid and changing to a verdigris green colour on exposure 

 to the air, and possessing, after this change, the faculty of rapidly decomposing any 

 small Alga3 with which they may come in contact. Stems and branches uniform, 

 destitute of any separate, leaf-like expansions, inarticulate ; sometimes cylindrical 

 and filiform, often exceedingly slender ; sometimes compressed ; and sometimes 

 flattened, leaf-like, and furnished with a distinct midrib, occasionally throwing off 

 lateral nervelets. The branching is frequently opposite, and almost always disti- 

 chous. Air-vessels none. Almost all bear, at some period of their growth, pencils 

 of delicate, jointed, confervoid filaments. In some, as in Desmarestia and Arthro- 

 cladia, these filaments are found on the growing apices, and on all the younger 

 portions of the frond, and appear to be intimately connected with the process of 

 cell-division then going on ; and they gradually fall away after the part has attained 

 its full size. In Arthrocladia a portion of them remains, and eventually supports 

 the fructification. In others, as in Sporochnus and Carpomitra, similar filaments 

 spring from and crown the receptacles of the fructification, and fall away when the 

 spores have arrived at maturity. 



The outward appearance of the fructification varies in the different genera of this 

 Order, but the differences are of a minor character. In all, the spores are attached 

 to branching, articulated filaments which issue from some part of the branches, 

 and are, therefore, external to the substance. But in some, as in all the American 

 genera, these filaments are free, either clothing the branches or forming pencil-like 

 VOL. rn. art. 4. ^ 



