76 SYNOPSIS OF BRITISH SEAWEEDS. 



who saw specimens of our P. simulwns during his visit to 

 England, pronounced them distinct, an opinion also enter- 

 tained by Mrs. Griffiths, and in which, though not without 

 misgivings, I concur. 



122. nigTescens {The blackish Polysiphonia) ; fronds robust, 

 rigid, and generally rough with broken brandies below, much 

 branched and bush y above \ the branches alternate, repeat- 

 edly divided in a pinnate manner; ramuli distant, elongated, 

 awl-shaped, alternate, the upper ones sometimes having a few 

 processes near the tips ; lower articulations short, upper ra- 

 ther longer than broad; siphons about twenty, >urrounding 

 a large tube ; ceramidia broadly ovate, sessile or nearlv so, 

 Harv. in Hook. Br. Fl, v. 2. p. 332. (Atlas, PI. XXVII. 

 Fig. 121.) 



Polysiphonia fucoides, Grcv. Hutchinsia nigrescens, Lyngb. H. 



fucoides, Hook. Conferva nigrescens, Huds. C. fucoides, 



Suds. 

 Hah. On rocks and stones, and attached to Algae, etc., between 



tide-marks. Perennial? Summer. Abundant. 

 This species varies considerably in appearance according 

 to the time of year at which the specimens are collected, 

 the autumnal or winter individuals being coarse and bushy, 

 with crowded ramuli, while those gathered in spring and 

 summer are of the feathery character represented in our 

 figure. Some are of a dark-purple, and others are of a 

 dull-brown, or pale ; but all become much darker and even 

 black in drying. From all the British species of the sec- 

 tion to which it belongs, P. rdgrescens may be known by 

 the distantly pinnated ramuli, the very large number of 

 siphons, and the comparatively wide central tube. When 

 bearing antheridia, the tips of the branches are yellow. 



123. affinis {The allied Polysiphonia)', filaments robust, elon- 

 gated, cartilaginous below, flaccid above, irregularly divided ; 

 branches patent, naked at base, multifid, and with an ovate 

 outline above ; ramuli very erect, simple or divided, acute ; 

 articulations multistriate, the lower two or three times longer, 

 the upper as long as broad ; siphons about sixteen ; ceramidia 

 ovate, stalked or subsessile, Moore in Ord.Surv. Londonderry, 

 Appendix, p. 11. t. 7. (Atlas, PI. XXVII. Fig. 122.) 



Hab. Carnlough, near Grlenarm, Ireland. On rocks, etc., in the 



sea, thrown up from deep water. 



Very closely related to P. nigrescens, from which it chiefly 



differs iu the greater length of the articulations of the stem, 



rather a variable character j and in the smaller number 



