ceramiacejE. 209 



The entangled tufts of this species are not uncom- 

 mon, and possess comparatively easily recognized ex- 

 ternal characters; at the same time, all the species of 

 this genus vary so much in different circumstances, and 

 are so apt to resemble each other in outward appearance, 

 that it is never advisable to trust the unaided eye to 

 determine their identity. Every specimen should be 

 submitted to the microscope, and the result of the ex- 

 amination recorded for future use. 



Ceramium ciliatum. The ciliated Ceramium. 



Fronds growing in dense tufts, very slender, and of nearly 

 the same diameter throughout, rigid, repeatedly forked, 

 with or without branchlets ; tips of the frond very strongly 

 incurved ; axils spreading ; nodes coated with a band of co- 

 loured cellules, and armed with a regular whorl of robust, 

 awl-shaped, colourless, three-jointed spines; internodes trans- 

 parent, those in the lower part of the frond several times 

 longer than broad, becoming gradually very short in the 

 upper part. Spore-clusters sessile on the sides of the 

 branches, embraced by three or four involucral branch- 

 lets ; tetraspores not very prominent, whorled round the 

 nodes alternately with the spines. 



The form of the spines, and the mode of their arrange- 

 ment, are the distinctive characters of this species. The 

 spines have three joints, the lower one much longer 

 than either of the others. They are whorled round 

 the nodes in a single, regular series, and all point to- 

 wards the top of the frond. This plant grows in pools, 

 or among stones, between the tide-marks, and is fre- 

 quently parasitic. It is annual, and in season in sum- 

 mer. 



