BROWN ALG^ 



139 



lead a parasitic life on other algae ; and the big Lamm- 

 arise, the crust-forming Ralfsiae so easily overlooked ; 

 Asperococcus, with its saclike frond ; and Cutlena, 

 with its two alternating generations, formerly described 

 as distinct genera under the names of Aglaozoma and 

 Cutleria— they all, and as many more, belong to the 

 Phaeosporae. 



Fig. 52. — Udothea (" Blake 



A few details may be given of the family of the Lamin- 

 ariaceae, or Kelps, this family being chosen because its 

 large members play such an important part in the 

 physiognomy of several coasts. 



When young they consist of a hold-fast, a stipe, and 

 a linear or expanded blade, which undergoes many 

 changes in the different genera. They live in the 



