( 104 ) 



on the upper branchlets, with two or three short spine-like involucral 

 ramuli. Tetraspores tripartite, pale when yoimg, deep red when mature, 

 partially immersed in the upper ("not ultimate ") branchlets, prominent, 

 forming a beaded ring round the upper part of the dissepiment. 



A very beautiful and delicate species, readily distinguished from the 

 two preceding by the absence of the lateral ramuli, which are only 

 represented by an occasional short, simple, curved, spine-like innovation. 

 The extremely delicate hairs that abundantly clothe joints of young 

 plants, are by no means peculiar to the species nor even to the genus, 

 as they are common to most of the marine Algse, and even to plants 

 of a higher, or perhaps even of the highest organisation, they are 

 perhaps nothing more than analogues of the pubescence that covers 

 the young shoots of most plants, even of trees of the highest order, 

 being perhaps meant as an additional protection to these tender parts 

 in the earlier stages of their growth, disappearing as the parts become 

 matm-ed and require no such aid (?) They are much more abundant on 

 the present than on any other species of the genus, and it is possible, 

 as Professor Harvey observes, that they may be connected with the 

 fructification, but their extreme delicacy, their simple structiure, 

 evanescent nature, and their being found the more sparingly down 

 nearly to the middle of the plant, has always appeared to us to militate 

 against that conclusion. 



EXPLANATION OF PLATE GUI. 



Fig. 1. — Cerainium strictum, natural size. 

 2. — Apex of raniulus. 

 3. — Ramulus with favella. 

 4. — Portion of same with tetraspores. 

 5. — Portion of stem. All magnified. 



