106 SPH^ROCOCCOIDE.E. v. 



My American specimens of this plant are neither numerous nor quite satisfac- 

 tory. One from Boston Bay is not unlike some of the smaller forms of the species 

 as known in Europe. It is about four inches long, partly dichotomous, partly 

 pinnated with lateral, simple laciniae, the margin closely fringed with slender, sub- 

 filiform, simple or slightly branched processes from a quarter to half an inch in 

 leno-th. The colour is dark red, inclining to purple ; and though it has perhaps 

 more the technical characters of C. jubata, its aspect and substance are those of 

 C. ciliata. 



The Halifax specimens were dredged in deep water, to which circumstance I 

 attribute their peculiarities. They are but two or three inches in height ; one of 

 them is half an inch wide at the widest part, but the usual breadth is from one to 

 two lines or less. The frond is cuneate at base, twice or thrice forked, the apices of 

 the last divisions drawn out into filiform points which are repeatedly forked toward 

 the summit. The margin is fringed with slender lobes, from one to two lines to 

 upwards of an inch in length, in the latter case often dichotomous. Can these be 

 RhodophylUs veprecula, J. Ag.? 



VII. GRACILARIA. Grev. J. Ao-. ref. 



&• 



Frond either filiform, compressed, or flat, narrow, carnoso-cartilaginous, dichoto- 

 mous or ii^regularly decompound, composed of two strata of cells ; the inner 

 stratum of large, roundish-angular longitudinal cells, more or less filled with 

 granular matter ; the outer of minute, coloured cellules in vertical lines. Concep- 

 tades sessile on the branches, hemispherical or conical, Avith a thick pericarp at 

 length opening by a terminal pore, containing, on an elevated basal placenta, 

 densely tufted, dichotomous, fastigiate, moniliforni spore-threads radiating to every 

 side ; spores evolved in the upper articulations. Tetraspores oblong, cruciate, dis- 

 persed among the surface cellules of the branches and ramuli. 



This genus, originally proposed by Dr. Greville in his Algce Britannicce, has been 

 amended by Prof. J. Agardh by the rejection of such species as do not accord with 

 the above characters. It is the same as the Plocaria of Endlicher, and, to a great 

 extent, as the first section of Kiitzing's genus Splicer ococcus. The name Plocaria 

 Candida was given by Nees von Esenbeck to the Ceylon moss of commerce ( Gra- 

 cilaria lichenoides?), and has been extended to the Grevillio-Agardhian genus by 

 Endlicher on the plea that it had the priority in order of publication. But I agree 

 with Professor Agardh in regarding the mutation of an established generic name 

 as being in this instance uncalled for, inasmuch as the name Plocaria (which has 

 very little the priority over ■ Gracilaria) was given in ignorance of the natural 

 afiinities of the plant so-called, Nees believing it to be a lichen ; nor is it very 



