V. RHODOMELACE^. 49 



similar but bipinnate, each of their pinna) being naked below and j)innulatc above. 

 The pinnules are very erect and taper to the base and apex. The tubes in the 

 specimen examined are nine or ten in the stem. The internodes are distinctly 

 visible in all parts of the frond; those of the main branches are very many times 

 longer than broad, and have the tubes often spirally twisted ; those of the smaller 

 branches and pinnaj are uniformly short, once and a half to twice as long as broad ; 

 and those of the pinnules are about as long as their breadth. The substance, though 

 tenacious, is very flaccid. The colour, probably full red in the recent plant, is a 

 dark red brown in the dried specimen. In drying, it does not adhere very closely 

 to paper. 



This is allied in many respects to P. afrorubescens, from which it differs in 

 tenuity and in general aspect, as well as in the much greater length of the inter- 

 nodes of the larger branches. These latter characters connect it with P. tenui- 

 striata of the Southern Ocean, and perhaps future obserA'ations may oblige us to 

 unite it to that species ; but at present we have not evidence to warrant our doing 

 so. 



24. PoLYSiPiiONiA nif/rescens, Grev. ; frond robust, rigid and rough with broken 

 branches below, flaccid much branched and bushy above ; branches alternate, de- 

 compound pinnate ; ramuli distant, elongate, awl-shaped, alternate, the upper ones 

 pinnulate near the tips ; internodes of the branches rarely shorter than their 

 breadth, often once and half to twice or four times as long as broad, multistriatc ; 

 tubes from twelve to twenty ; conceptacles ovate, sessile or neai'ly so. Ag. Sp. Alg. 

 2, p. 69- Kutz. Phyc. Gen. t. 50,/. 4. Sp. Alg. p. 813. 



Of this most variable plant I have received the following forms from America : — 

 fucoides ; robust, excessively branched and bushy ; branches sub-spirally 

 inserted, many times pinnated, the lesser branches sub-bipinnate, fastigiate 

 and sub-corymbose ; pinnules naked below, pinnulate above ; internodes of 

 the branches once and half to twice, of the ramuli once and half as long as 

 broad ; tubes of the stem varying from twelve to twenty. Pol. nigrescens, 

 Harv. Phyc. Brit. t. 277. P. fucoides, Grev. Edin. p. 308. Conferva fucoides, 

 Dillw. t. 75. E. Bot. t. 1743. 



A ajfnis ; robust, elongate, repeatedly pinnate but rather laxly branched, the 

 principal branches naked below, decompound pinnate above ; the lesser 

 branches somewhat fastigiate and corymbose ; internodes of the brandies 

 three or four times, of the ramuli once and half to t-wice as long as broad ; 

 tubes 15-16. Pol. affmis Moore ; Harv. Phyc. Brit. t. 303. 



7. plumosa ; stem setaceous, undivided, j)innated with lateral, alternate or secund, 

 sub-distant, decompound branches ; branches lanceolate in outline, three or 

 four times pinnate, plumose, the apices not lastigiate ; ramuli very slender, 

 erecto-patent ; internodes of the l)ranches 2-4 times, of the ramuli once and 

 half to twice as long as broad ; tubes seventeen or eighteen. 



S. gracillima ; stem setaceous, undivided, pinnated with capillary elongate 



VOL. IV. ART. 5. ^ 



