( 186 ) 



One of the most graceful and beautiful, even in a genus in which grace- 

 fulness and beauty constitute their characteristic featui-e. When the long, 

 slender, delicate pinnse are well grown and free from parasites, and either 

 waving gracefully in its native element or carefuUy spread out on paper, 

 a more beautiful species will scarcely be found in any genus. Confined 

 to the southern shores of the kingdom, and there not hitherto found in 

 anything like plenty, it is considered one of our rarer species, and should 

 be carefully looked for about or a little beyond low water, on somewhat 

 muddy rocks. 



Dr. Harvey has pointed out its close affinity with C. thuyoideum, from 

 which it is chiefly distinguished by its larger size, more regularly dis- 

 tichous, branching, somewhat more closely placed divisions, and somewhat 

 shorter joints. Its beautiful fern-like fronds are said to have suggested 

 to Mrs. Griffiths the name of " Fern-leaf Alga," a term at once euphonious 

 and appropriate. 



CALLITHAMNION GRACILLIMUM. 



EXPLANATION OF DISSECTIONS. 



Fig. 1. — Portion of branch with tetraspores. 

 2. — Portion of branch with favellse. 

 3, 4. — Tetraspores. All magnified. 



