136 ECTOCAEPACE^.— Ch^topteris.— Sphacelaeia. 



11. CHiETOPTERIS. Kutz. 



Frond filiform, compressed, inarticulate, disticliously pinnate. Stem cellular, 

 omposed of a triple stratification of cellules ; the central portion of longitudinal, 

 prismatic cells, horizontally connected ; the intermediate of roundish cells ; the 

 outer of minute cellules. Fructification: — spores (unknown). The sphacelate tips 

 of the pinnated ramuli contain a sporaceous mass or propagulum. 



This genus has the habit of Sphacelaria, with which it has until recently been 

 associated by authors, and a structure of stem similar to that of Cladostephus. It 

 is therefore exactly intermediate between these genera. 



1. CBMTOFTiEms plumosa, Kiitz. ; stems naked at the base, elongated, irregularly 

 branched ; branches pectinato-pinnate ; pinnse opposite, simple, very long, closely 

 set. Kiitz. Sp. Alg. p. 468. J. Ag. Sp. Alg. 1. p. 41. Sphacelaria plumosa, Ag. 

 Harv. Phyc. Brit. t. 87- Conferva pinnata, E. Bot. t. 2330, {left hand fig.) 



Hab. On the shores of Greenland, J. Agardh. Arctic Coast, Mr. Seeman. (v. v.) 



Fronds from two to four or six inches long, setaceous, naked below, irregularly 

 and much branched above. Branches alternate or secund, or frequently tufted, one 

 or two inches long, simple, closely pectinated along their whole length with slender, 

 articulated, distichous ramuli. These ramuli are from one to three lines long, oppo- 

 site, a pair growing from every joint of the branch. 



This beautiful plant is peculiarly a northern form, and though it reaches the south 

 of England, is there of much smaller size than on the shores of Scotland. The 

 branches resemble delicate feathers. 



III. SPHACELARIA. Lyngb. 



Frond filiform, articulated, distichously branched, rigid, pinnated, rarely subdicho- 

 tomous. Articulations of the stem and larger branches composed of several cells 

 radiating from a central point. Apices of the branches distended, membranous, 

 containing a sporaceous mass or propagulum. Spores ovoid, having a pellucid 

 perispore, affixed to the branches. 



