134 ECTOCARPACE^.— Cladostephus. iv. 



These plants are most numerous in the temperate waters of the ocean, diminish- 

 ing toward the warmer and the colder zones. On the American coast they are 

 more frequent on the shores of the northern and midland States ; and in Europe 

 on the coasts of Britain and France. Several are, however, found in the Mediter- 

 ranean and Adriatic. They are all plants of small size, though few come within 

 the limits of strictly microscopic objects. The genera are widely dispersed, all 

 nearly cosmopolitan. 



SYNOPSIS OF THE NORTH AMERICAN GENERA. 



Suborder 1. SPHACELARiEiE, Frond rigid ; each articulation composed of numer- 

 ous cells. 



I. Cladostephus. Stems inarticulate. Ramuli whorled. 



II. Chjetopteris. Stems inarticulate. Hamuli pinnated. 



III. Sphacelaria. Whole /roncZ articulate, pinnately branched. 



Sub-order 2. EcTOCARPEiE. Frond flaccid ; each articulation composed of a 

 single cell. 



IV. EcTOCARPUS. Capillary, soft, much branched. 



I. CLADOSTEPHUS, Ag. 



Frond cylindrical, inarticulate, densely clothed with whorled, articulate, short, 

 subsimple ramuli. Stem cellular, composed of a triple stratification of cellules ; 

 the central portion of longitudinal prismatical cells horizontally connected ; the inter- 

 mediate of roundish cells ; the outer of minute cellules. Fructification^ ellipsoidal 

 spores, having a hyaline perispore, and borne on little stalks on accessory ramuli. 

 The sphacelate tips of the whorled ramuli also contain a sporaceous mass or pro- 

 pagulmn (?). 



Readily known from the rest of the order by the densely-set, quadrifarious, 

 whorled and imbricated ramuli. The two following species are very closely allied 

 to each other, and perhaps not permanently distinct, the differences indicated 

 arising from difference of locality. 



