232 CERAMIACE^. .^. 



these primary branches bear a second or third series of similar lesser branches. 

 Branches densely set with short, spirally inserted branchlets, the lowest of which 

 are simple or bifid, the upper more compound or somewhat plumulate ; the plumule 

 either pinnate or bi-pinnate, the upper pinnules being frequently pinnellate. Hamuli 

 subulate, mostly incurved, tapering to a fine point. Articulations variable in length; 

 those of tlie main stem generally veiny, sub-opaque ; those of the branches destitute 

 of veins except in very old specimens, swollen at the nodes, with narrow endo- 

 chrome and thick, hyaline walls ; those of the ramuli from three to four or five 

 times as long as broad. Tetraspores mostly solitary, near the middle of the ramuU. 

 Favellx in pairs on shortened plumules. Colour^ a fine, dark red. Substance rather 

 soft. It closely adheres to paper in drying. 



The original specimens received from Prof Bailey appeared, when I first 

 examined them, to constitute a well marked species, readily distinguishable from 

 all others ; and specimens sent to me from various correspondents, and others 

 collected by myself at New York, agree with them in all essential characters. But 

 many other specimens have also reached me which vary greatly from the type, 

 especially in the length of the articulations, and yet which are too closely connected 

 with the first specimens to warrant their specific separation. In our var. ^ boreale, 

 which is the common form of the species in Massachusetts Bay, the frond is more 

 pellucid, of a brighter colour, with longer internodes. But the most delicately 

 beautiful feathery specimens are those received from Dr. Roche of New Bedford, 

 Avhich are so unlike the New York plant, that but for the Boston variety just 

 mentioned, I should hardly have ventured to unite them. Again, the most robust 

 forms, with shortest joints, approach inconveniently near to C. tetragonum, from which 

 species the more delicate ones appear widely different. Future observations may 

 perhaps show that Dr. Roche's specimens should be separated ; but if this be done, 

 what I now regard as a single species must be split into four or five. 



Plate XXXV. B. Fig. 1. CALLiXHAMisrioN Bailey i ; the natural size. Fig. 2, 

 plumule and part of lesser branch of the var. /3 boreale ; jig. 3, favellce from the 

 same ; Jig. 4, part of stem of the normal variety (a); figs. 5 and 7, plumules from 

 the same ; fig. 6, a ramulus, with tetraspores ; the latter figures more or less 

 magnified. 



Sect. 2 Rosea : Fronds capillary or byssoid, densely tufted., articulated throughout, 

 {the older parts of the stem veiny, but not opaque) decompound-pinnate ; pinnce and 

 pinnules alternate. 



4. Callithamnion squarrulosum ; frond setaceous, distichous ; stem and larger 

 branches veiny toward the base, but visibly articulate throughout, percurrent, set 

 with lateral, flexuous, alternate branches, which are naked or with a few squarrose 

 ramuli below and alternately decompound beyond the middle ; secondary branches 

 of unequal lengths, very patent, laxly set with alternate, simple, bifid or pinnulate 

 divaricating, obtuse ramuli ; articulations four or five times as long as broad, the 

 cell -walls thick and endochrome narrow. 



