220 BRITISH CORALLINES: 



layer of a soft, transparent, colourless matter ; this transparent 

 covering is spread completely over the free ends of all the 

 branches, is thickest in the centre, and tapers gradually to the 

 sides, where no trace of it is seen ; on the surface of this matter 

 we can distinguish very minute tubercles or papillae, likewise 

 transparent, but which do not appear to have any motion. I 

 have not observed this on any other part of the coralline ; and, 

 as it appears to have escaped notice, and may possibly have 

 some connection with the mode of growth of a substance whose 

 nature is still perfectly unknown, I have thought it worthy of 

 being suggested to the attention of zoologists." Dr Grant. 



Cor. officinalis appears first in the guise of a thin, circular, 

 calcareous patch of a purplish colour, and in this state is com- 

 mon on almost every object that grows between tide-marks. 

 When developing on the leaves of Zostera, or in other unfavour- 

 able sites, these patches are usually pulverulent and ill-coloured, 

 green or white, and never become large ; but, in suitable situ- 

 ations, they continue enlarging in concentric circles, each mark- 

 ed with a pale zone, until they ultimately cover a space of seve- 

 i-al inches in diameter. The resemblance which, in this condition, 

 the cnist has to some crustaceous fungi, more especially to the Po- 

 lyporous versicolor, is remarkably exact, and neither is it less 

 variable than the fungus in its growth, the variations depending 

 on the nature of the site from which it grows. If this is smooth 

 and even, the foliaceous coralline is entirely adnate and also 

 even, but if the surface of the site is uneven or knobbed, the 

 coralline assumes the same character. If it grows from the edge 

 of a rock, or on the frond of a narrow sea-weed, or from the 

 branch of the perfect coralline, the basal laminae spread beyond 

 in overlapping imbrications of considerable neatness and beauty : 

 they are semicircular, wavy, either smooth or studded with scat- 

 tered granules, and these granules may be either solid or perfo- 

 rated on the top. Such states of the coralline have been de- 



