THE MARINE BOTANIST. 99 



/Tetraspores immersed in the branches and 

 ramuli. Laurenciacese. 



6 ( Tetraspores either spread over the frond, 

 or in cloud-like spots. 



Rhodymeniaceae. 



The sea-plants forming- the red series thrive and 

 assume their richest hues in deep water 5 in shallow 

 pools exposed to the sunlight, they never attain their 

 full and natural colour, but degenerate to a greenish 

 or yellowish white ; this is particularly remarkable 

 in Laurencia pinnatifida, Chondrus crispus, and 

 Ceramium rubrum. The double system of fructi- 

 fication, delicately membranaceous, leaf-like, or 

 often filamentous fronds of a red or pinky hue, soon 



\ changing colour and decomposing in fresh water, 

 form the main characteristics of this series. In 

 the Coralline tribe, there is in the outward struc- 

 ture and appearance of the species a remarkable 

 dissimilarity from the other red sea-weeds, arising 

 from the presence of carbonate of lime in their 



! tissues, which gives them, a stony hardness, and 



