PUCACSJB. 



269 



the first, F. nodosus, F. fureatus, and F. vesiculosus are the most com- 

 mon species on our Eastern coast ; the latter also occurs on the Pacific 

 coast; both are known as Rock-weeds. Sargasaum vulgare is common 

 on the Atlantic coast ; 8. bacciferum, the Gulf-weed, is found in the 

 warmer parts of the several oceans, and in mid- Atlantic covers an im- 

 mense tract known as the Sargasso Sea. 



(d) The species of Fucus and Sargassum are washed ashore in great 

 quantities during violent storms, constituting the bulk of the " wrack " 

 of the coasts. They furnish valuable manure lor enriching the soil, 

 and are largely used for this purpose. From their ashes alkalies and 

 iodine are obtained. From the hardened stems of a species of Lami- 

 naria walking-sticks, whips, knife handles, etc., are manufactured. 



(e) In the Silurian period Facoides antiquus represented the order 

 Fucaceae, while Lamiiuirites, Harlan>a, etc., probably represented the 

 Phseosporese. In the Devonian both these orders were abundantly 

 represented. Fucus, Sargnxsum, and other genera were already in 

 existence during Tertiary times. 



AHHANGEMENT OP THK CLASSES AND ORDERS OF THE OOSPORE^E. 



