condition it is sometimes a little difficult to distinguish specimens 

 of Chorda lomentaria, from narrow ones of Asperococcus echi- 

 natus, except by their more chestnut colour and more polished 

 surface, and Capt. Carmichael has described such individuals 

 under the name of A. castaneus. 



Authentic specimens of Kiitzing's Chlorosiphon Shutileworthia- 

 mis, obligingly communicated to me by that author, appear to me 

 to belong to the very youngest state of the present plant. They 

 were collected by Mr. Shuttleworth in the West of Ireland, 

 where our Chorda is abundant. 



Fig. 1. fronds of Chorda lomentaria, of various ages; — the natural size. 

 2. Transverse section of the frond. 3. Small portion of the same: — more 

 highly magnified. 



