38 BRITISH SEA-WEEDS. 



jointed, 'divided internally into cells, pointed at the apex, 

 fructification in terminal, tuber&ulated receptacles. 



The name of this genus is derived from the Greek 

 words als, the seag &mk*dfm, an oak. Of the two species 

 that are known, one has -onty beeri found in North 

 American waters, and the other is common on all parts 

 of the. British coast and the adjacent shores of Europe. 



Halidrys siliquosa. Podded Sea-oak. 



Erond repeatedly- pinnate.-- Air ^vessels oblong, with a 

 bristle-like point. ,: •. 



This Sea-weed is a perennial, and maybe found at all 

 seasons, in pools between high- and low- water mark. It 

 varies in size from a few inches long in shallow water to 

 three or four feet at greater depths. 



Genus III. CYSTOSEXRA. 



... Root a conical .disc: .Erond .shrub-like, having a woody 

 stem with alternate branches.. Air-vessels of one cell in 

 the substance of the branches.. , , Eructification at the ends 

 of the branchlets. •. ..._-,, rv j I0J 



The name Cystoseira, from the (jreek words kustis, 

 a bladder, and seira } ; a string, has reference to the ar- 

 rangement of the air-vessels. The larger proportion of the 

 twenty species which compose this genus are found in 

 the Mediterranean Sea, and the reriiairrder, with the ex- 

 ception of one or two which grow in America, frequent 

 the shores of Europe. They appear to form the con- 

 necting link between the warmth-loving Sargasso, and 

 -the Fuel, wlrieh delight in dold'er climates ; and as in geo- 

 graphical position, so also in structure they are interme- 



