eye, a crustaceous Lichen, than an Alga, but its structure and 

 fructification prove it to be widely different from any Lichen. 

 There is a curiously close resemblance, both in the habit, the 

 structure of the frond, and the outward character of its fruit, 

 between Balfsia and Peysonettia ; yet, according to the received 

 notions of arrangement, these plants must be referred to opposite 

 parts of the system. They are, however, closely analogical forms, 

 in the families to which they respectively belong. Except for 

 the colour, and the different formation of the spores, there 

 would be little to distinguished them. 



Balfsia deusta is a very common species throughout the 

 Northern Atlantic Ocean, and probably extends along most of 

 the shores of Europe, North Asia, and North America • though 

 not yet recorded from the latter. Its crustaceous habit may 

 often cause it to be over-looked. 



Endlicher has confounded it with the very different Hilden- 

 brandtia rubra (which is also common on the British coast); and 

 Areschoug has, still more unhappily, put it into the same genus 

 as Cruoria jpellita, with which, in structure, it J>as very little 

 connection. The resemblance between these is purely external. 



The fructification of Balfsia is either very rarely produced, or 

 so difficult to find, owing to its obscurity, that it is rarely seen. 

 It was first observed, I believe, by Dr. Johnston, who commu- 

 nicated the specimens to Mr. Berkeley, by whom they were des- 

 cribed.. Though myself familiar with this plant for many years, 

 I had never seen the fruit, until I received fertile specimens from 

 Dr. Dickie of Aberdeen, and from these I have made my analysis. 

 On the west coast of Scotland and of Ireland this plant is exces- 

 sively abundant, and its patches reach a large size. Devonshire 

 specimens, communicated by the Rev. Mr. Cresswell, are much 

 inferior. 



Fig. 1. Ralfsia deusta, young and old fronds : — of the natural size. 2. Ver- 

 tical section of the frond. 3. Filaments of which the frond is composed. 

 4. Spores, among the filaments of a wart. 5. A spore and its filaments, 

 separated : — all more or less highly magnified. 



