the branch ; here when the ramuli are fertile the whole of the 

 upper portion of the ramulus becomes the fruit. Such a cha- 

 racter, if constant, would very well serve for a specific diagnosis, 

 but its constancy has yet to be tested. Our E. longifructus rests 

 at present upon a solitary specimen preserved in the herbarium 

 of the Rev. J. H. Pollexfen, of Clapham, to whom I am indebted 

 for my knowledge of this plant, and who has allowed me to 

 abstract one of the lateral branches of his specimen. Persons 

 visiting Orkney would do well to look carefully after the Ecto- 

 carpi, among which many more forms may yet be noticed. The 

 characters of these plants cannot always be detected by the naked 

 eye, nor are they easily recognisable except when in fructification. 

 I am fully sensible that it is unsafe to propose new species from 

 an inspection of individual specimens, but there are cases in 

 which this course may safely be taken ; and it will be remem- 

 bered that Ectocarpus Hincksiae is an instance of a species 

 founded, like the present, on a solitary specimen picked up by a 

 lady, but which, in a short time, was ascertained to exist on 

 many distant shores, and which is now well established. I hope 

 the present experiment may be equally successful. 



Fig.]. Ectocarpus longifructus: — the natural size. 2. A branch: — mag- 

 nified. 3. Silicules from the same : — highly magnified. 



