CERAMIACEjE. 211 



and general character. They were formerly described 

 as varieties of the same plant. 



Ptilota plumosa. The feathery Ptilota. 



Frond nearly flat, thicker in the middle than at the edges, 

 very much hranched ; branches and branchlets pinnate, and 

 opposite, of similar form, but of various sizes, a long and a 

 short branch being frequently opposite to each other; the 

 ultimate divisions of the frond comb-like, their teeth pointed, 

 ■without apparent joints. Spore-clusters formed at the tips 

 of the branchlets, nestling among several long, simple, acute, 

 involucral branchlets ; tetraspores at the tips of the teeth 

 of the comb-like branchlets. 



This is almost exclusively a northern species, and has 

 not been found on our southern coasts. In the locali- 

 ties where it grows, the stems of the large specimens of 

 Laminaria digitata, which are thrown on shore in sum- 

 mer and autumn, are frequently densely clothed with its 

 dark-crimson, feathery fronds. When fresh it is a very 

 handsome plant, and is an interesting object for the mi- 

 croscope. It shrinks much in drying, and does not ad- 

 here closely to paper, but, notwithstanding these disad- 

 vantages, it makes a beautiful specimen for a collection. 



Ptilota elegans. The elegant Ptilota. 



Frond three to six inches long, flaccid, very much 

 branched, pinnately divided; all the younger pinnae are 

 jointed, and composed of a single row of large cells, ob- 

 tuse at the tips ; the larger branches are alternate, the 

 lesser opposite, but not always the same length. Spore- 

 clusters in pairs, naked, or surrounded by a few involucral 

 branchlets ; tetraspores on the tips of the ultimate branch- 



p3 



