236 CERAMIACE^. v. 



characters are not sufficiently marked. Meantime I indicate it above as var. B 



Waltersii. 



8. Callithamnion Dietzice, Hooper ; fronds capillary, pellucidly articulate nearly 

 to the base, the lower part of the percurrent, distichously-pinnate stem veiny ; 

 branches alternate, simple, set at each node with short, alternate, sub-simple or 

 pinnato-dichotomous plumules, and often terminated by a dense fascicle of ramuli ; 

 rachides zig-zag ; articulations of the stem six or eight times, of the rachides three 

 or four times, of the ramuli eight or ten times as long as broad ; apices sub-attenu- 

 ate, obtuse, or sub-acute ; tetraspores elliptical, tripartite, solitary on the uppermost 

 ramuli. 



Hab. Greenport, Mrs. Dietz. (v. s. in Herb. Hooper.) 



Fronds tufted, two to three inches long, as thick as human hair. Stem either 

 simple or divided near the base into several, long, simple, erect, main divisions, set 

 throughout with alternate, patent, elongate, simple branches, which, in luxuriant 

 specimens, probably bear a second set of similar smaller ones. Outline of the frond 

 ovato-lanceolate. Branches alternate or sometimes secund, sub-distichous, articulate, 

 each node bearing at alternate sides of the branch, a pinnato-dichotomous branchlet 

 or plumule. Plumules with a ziz-zag rachis, either short with three or four pinna?, 

 or lengthening out, simply pinnate in the lower half, bi-pinnato-dichotomous above, 

 each pinnule ending in a dense tuft of undeveloped ramuli. Articulations of the 

 lower part of the stem three or four times as long as broad, veiny, with a narrow 

 tube ; of the branches mth thick, pellucid walls, six or eight times ; of the rachides 

 of the plumules shorter, but of the ultimate pinnules six to eight or ten times as 

 long as broad. Colour^ a beautiful rosy-red. Substance soft, closely adhering to 

 paper. Tetraspores tripartite, elliptical, solitary on the ultimate ramuli, formed 

 from the suj)pressed arm of a furcellation. 



Of this plant I have yet seen but few specimens ; too few to form a decided 

 opinion on its specific validity. Notwithstanding its pinnate habit I am not with- 

 out fears that a more extensive suite of specimens may show it to pass oif into one 

 of the forms of C. corymhosum or C. versicolor. The specific name is bestowed by 

 Mr. Hooper in honour of its discoverer, Mrs. Dietz of New York. 



Sect. 3. Cortmbosa ; Fronds setaceous or byssoid, alternately decompound ; the secon- 

 dary branches and ramuli dichotomous, corymboso-fastigiate. 



9. Callithajinion corymhosum^ Ag. ; fronds tufted or solitary, flabelliform, pellu- 

 cidly articulate throughout ; stem and lower branches setaceous below, attenuated 

 upwards to a byssoid fineness, decompound, much branched ; upper branches 

 byssoid, excessively flaccid, pinnato-dichotomous or alternately or secundly decoin- 



