CeramiecB.'] ceramium. 199 



a tuft of C. acantlwnotum, natural size ; and tlie figure on 

 the left is a branch magnified to show the spines.) 



Hab. On rocks at half-tide level. Annual. 



This may be known from C. dliatum^ which it resembles, 

 and with which it has in general been confounded, by its 

 colour, which is darker ; by its tufts, which are shorter and 

 more compact ; but more especially by the solitary three- 

 jointed spine which arms the outer margin of every joint. 

 The tetraspores encircle the joint, and the favella ensconce 

 themselves within the incurved ramuli. 



In Ayrshire this species is by far more common than C. 

 ciliaUmiy for which it was long taken. At Saltcoats, it is 

 found at half-tide level on rocks covered with young mussels, 

 seeming to like to grow among them. At Portincross and 

 in Ai'ran, it is found in abundance, and the tufts are more 

 than double the size of the tuft in the Plate. It does not 

 adhere very well to paper, unless when it is young. 



5. Ceramium echionotum, /. Agardh. 



Ilab. It is not uncommon. It has been found by Mrs. 

 Grifiiths, Eev. Mr. Hore, Mr. EohlafP, Miss Ball, Professor 

 Harvey, and Mr. Wm. Thompson. 



At the time I discovered this species on the wall of the 

 pier at Saltcoats, its name was not found in any of the lists 



