irregular cells ; a transverse section shows four large cells surrounding the 

 axile cell, and many rows of smaller exterior cellules, ending in the peri- 

 phery formed of coloured cells. The colour of the frond when growing is a 

 dark brownish- or purplish-red ; when dry it is black. The substance is firm 

 and tough, not very soft, and in drying the younger parts adhere closely, 

 the older loosely, to paper. 



The several so-called species of the genus Acanthophora do not 

 rest on very certain or absolute characters, and in adding one to 

 the number, perhaps I ought to make an apology. The present 

 is still larger, more tree-like, and more densely ramuliferous than 

 A. deudroides, its nearest ally; and is of a darker colour, and 

 more rigid substance. It is quite different in habit from A. Tas- 

 manica, Sond., for which I formerly mistook it ; nor is there any 

 other species of similar aspect. The microscopic characters, 

 throughout this genus, are but too similar. Still there are ap- 

 preciable differences in the spine-like ramuli, as well as in the 

 general ramification. 



Pig. 1. AcANTHOPHORA ARBOKEA, — the natural Size. 2. Small portion of the 

 frond, showing the form and insertion of the spine-like ramuli. 3. A cross 

 section of a branch. 4. A ceramidium on its peduncle : — the latter figures 

 variously magnified. 



