ULVACEiE. 247 



weeds. It is annual, and may be found in shore-poolsj 

 and at greater depths on most parts of our coasts during 

 summer and autumn. 



Bryopsis hypnoides. The Hypnum-Iike Bryopsis. 



Fronds growing in tufts, from four to six inches high, 

 much branched ; branches loug, rod-like, set on all round 

 the stem, either simple or bearing a second similar series ; 

 branchlets irregularly pinnate, yery slender and delicate, 

 generally confined to the upper part of the branches. 



There is some general resemblance between this spe- 

 cies and the last, and there are exceptional forms of 

 each, whose identity it is not always easy to determine. 

 The distinctive characters of B. hypnoides are its nu- 

 merous long branches, and its soft sUky texture. This 

 species is annual, and flourishes in summer. It grows 

 on rocks or sea- weeds in shady pools of various depths, 

 and is pretty generally distributed round our coasts. 



Order XXII. ULVACE^. 



Frond of a Orass-green or Furple colour, composed of many 

 minute cells, forming a thin membrane of indefinite shape, 

 flat or tubular, simple or branched. Fructification, ciliated 

 zoospores developed in the cells of the frond. 



This Order affords an illustration of the natural alli- 

 ance of sea-weeds of different colours. Most of the 

 genera composing it are of the bright, pale green colour, 

 which characterizes the division ; but two, Porphyra and 

 Bangia, are purple. Some writers have separated these 

 from the remainder, and placed them in the Red divi- 



