CERAMIACEiE. 227 



cally on other Algre, and on rocks near low-water mark, 

 and is annual. 



Callithamnion fasciculatum. The fasciculate 

 Callithamnion. 



Fronds tufted ; branches erect, level-topped ; plumules 

 elongate, erect, linear-obovate, truncate ; pinna? long and 

 flexuous, the lowermost simple, appressed, the upper 

 branched, spreading ; articulations veined, from twice to four 

 times as long as broad, those of the pinna? contracted at the 

 joints. Favella? on the joints of the upper branches : tetra- 

 spores tripartite, solitary, near the base of the pinnules. 



Only a single specimen of this species is known to 

 have been found, and it is therefore impossible to decide 

 with certainty that it is distinct. It is figured by Dr. 

 Harvey in the ' Phycologia Britannica/ and Professor 

 Agardh inserts it in his ' Species Algarum ;' I have, there- 

 fore, copied the description given in the former work. 



Callithamnion Borreri. Borrer's Callithamnion. 



Fronds growing in tufts, from one to four or five inches 

 long, much branched from the root in a fan-shaped manner, 

 distinctly jointed throughout ; branches set with two or 

 three series of spirally inserted lesser branches, naked below, 

 plumulate above ; plumules bare for about half their length, 

 set with simple pinna? for the remainder, the lower pinna? 

 longest, becoming gradually shorter towards the apex ; arti- 

 culations of the branches two to five times, of the branchlets 

 about twice as long as broad; throughout the frond the va- 

 rious divisions spring from each joint, and are regularly al- 

 ternate. Favella? in pairs, without stalks, on the plumules ; 

 tetraspores roundish, on the inner side of the pinna? of 



q 2 



