the generic Character of Ulva^ ^c. 55 



This beautiful fpecies was found on the beach at Yarmouth by 

 Mr. Wigg, at the fame time with the precv-ding one ; but has fince 

 been difcovered growing on the rocks at Cromer, on the Norfolk 

 coaft. It very much refembles fome of the varieties oi Fucus ciliatusy 

 particularly that which is called by Gmelin llgulalus, and has doubt- 

 Jcfs been confounded with it; but the fructification not only proves 

 it to be a very different plant, but alfo points it out clearly as be- 

 longing to the genus Uiva. It differs alfo effentialiy in never 

 having the ligulated procelTes, nor any part of the frond armed with 

 cilia. This fpecies varies very much in fubft^ance, being fometimes 

 found extremely thin and tender, and at others almoft approaching 

 to cartilaginous. The frond moft frequently branches dire£tly from 

 the root, and is dichotomoufly divided throughout; but fometimes 

 it is entire for half its length, and then is divided, in a palmated 

 form, into three or four fegments, which are again branched and 

 fubdivided. In either cafe, the fegments are always linear, the ter- 

 minations bifid, and ufually acute, and the margins clothed with 

 ligulated procefTes of the fame fubflance as the refl of the frond. 

 Immediately above the root it is always extremely narrow, pro- 

 ceeding as it were from a point, but is diredly dilated, which gives 

 the whole a cuneated form. The fru6tification confifts of minute 

 dark red grains or feeds, always fingle, but thickly fcattered on both 

 fides of the frond. 



Ulva decorticata — fronde tereti ramofa, ramis fubdichotomis : 

 apice attenuatis obtufis. Species nova. 



Radix nulla nifi bafis frondis paululum explanata — Frons 

 teres, propc bafin ramofa, 6-pedaHs et ultra, 4lineas lata — Rami 

 fongifTimi, femel vel bis nee ultra dichotomi, ad bafin et ad di- 

 chotomiam compreflTijCaeterum filiformes, apice attenuati obtufi. 



— Subflantia 



