THE MARINE BOTANIST. 3 



In this scries of the Algae are included the 

 largest known examples of marine vegetation ; 

 these grow in deep water^ but the majority of the 

 olivaceous kinds are found about half-tide level : 

 when growing in deep water^ they become either 

 of a brown or nearly black colour; the olive hue 

 is, however, generally observable in them, and it 

 is only during the process of decay that they 

 ever assume a grass -green tint; this is the case 

 in the Sporochnacese, which soon change from a 

 yellow-green to a verdigiis-green, when exposed to 

 the air. The Fucacese are characterised by tough 

 and leathery fronds, often furnished with air-vessels ; 

 they are not remarkable for their delicacy or 

 beauty, but their ft-uctification is distinct and 

 well developed, and affords an interesting jBeld 

 for microscopic observations. The Fuci may truly 

 be termed the weeds of our shores, occurring as 

 they do in such frequency, growing indifferently 

 on all substances between tide marks. Fucus 

 Mackaii is the only rare species, and this is confined 

 to the north of Ireland and Scotland. Omitting 



