158 SEA MOSSES. 



low-water mark The fronds are from six to twelve 

 inSies high, cylindrical, as thick as a pack-thread, 

 in full-grown plants, much slenderer in others, fine 

 as thread or hair in young plants, and in var. 

 Rochii. In the common form, the main stem and 

 branches are cartilaginous, stiff, and when dry, hard 

 and harsh, and quite black. From the leading stem, 

 which runs to the top of the plant, the branches 

 spread out on all sides, the lower being the longest, 

 often as long as the main stem — gradually short- 

 ening towards the top. The branches are all more 

 or less naked below. But, towards the end, they 

 divide and sub-divide rapidly in alternate ramifica- 

 tions, so that the small branchlets are much 

 crowded, and, on paper, the primary and secondary 

 branches seem thereby to terminate in little brooms. 



This is true only of the full-grown, typical forms, 

 and of the var. gracilis^ a most excellent representa- 

 tion of which appears in Plate IX. The normal form 

 differs from this only in being more robust, of a 

 less regular habit, and of a much darker color. 

 The var, Rochii is much finer and softer, and the 

 end branches are quite separate, but tipped with a 

 very fine pencil of hairs. This is the early spring 

 form, and is found chiefly south of Cape Cod. I 

 have an exquisite specimen collected by Mr. Young, 



