240 CRYPTOGAMIA ALGvE. 



series of small beads alternately coloured and pellucid. 

 The articulations of the main filaments are twice as long 

 as broad; but in the smaller branches the length and 

 breadth is about equal. The fruit, as I have observed it, 

 consists of imbedded tubercles, arranged in irregular circles 

 round the joints of the extreme branchlets. 



4. C. ciliatum, tufted, much branched, fine red, pellucid ; 

 branches dichotomous, the ultimate ones remarkably forcipate ; 

 articulations longer than their diameter, areolar, the joints whorl- 

 ed with minute prickles. HOOK. Scot. ii. 85. GREV. Fl. Edin. 

 311. Conferva ciliata, LIGHT F. Scot. 998. DILLW. Con/, p. 77, 

 t. 53. Eng. Bot. t. 2428. 



Hab. On rocks and algce, not common. 



Grows in small bushy masses, 1 or 2 inches in height. The 

 spinous whorls of the joints are only to be discovered with 

 the microscope, and their presence affords, perhaps, the 

 principal distinction between C. ciliatum and diaphanum. 

 I have, however, examined some specimens of the latter, in 

 which the joints, of the extreme branches in particular, 

 were armed on the external side with similar prickles, one 

 to each articulation ; and had they not been larger and 

 more robust than is usual with C. ciliatum, I know not to 

 which species these specimens could have been referred. 



143. CALLITHAMNION. 



1. C. purpurascens, purplish-red, tufted, excessively branched, 

 slender ; branches alternate, pinnate, the branchlets patent, al- 

 ternate, tapered ; articulations of the branches three times their 

 diameter, of the branchlets scarcely twice, almost moniliform; 

 fruit in lateral round sessile capsules on the branchlets. Confer- 

 va purpurascens, Eng. Bot. t. 2465. Ceramium thuyoides, AGARDH. 

 Callithamnion roseum, GREV. FL Edin. 511. 



Hab. On rocks and other algae, frequent. 



For the name and synonyms attached to this beautiful spe- 

 cies, I am indebted to Mr ARNOTT. It grows in small 

 remarkably dense tufts of a dull reddish colour, and about 

 an inch in height. Each plant may be compared to a 

 delicate bushy shrub in miniature. The main branches 

 are somewhat flexuose and irregular, but the branchlets are 

 regularly alternate and patent. They agree almost exact- 



