FLUSTRA. 353 



Fhistra may be seen every day on our shores, and yet many, 

 year after year, have paced the shore without ever observing 

 them, or only regarding them as so much grey crust, quite 

 undeserving of their attention. 



9. Fltjstra coriacea, E. Forbes, 



Hab. On old shells. Isle of Man, Prof. Torbes ; Fowey 

 Harbour and Peterhead, not uncommon, Mr. Peach; on 

 old shells, dredged off Sana Island, Mr. Hyndman. 



The cells broadly elliptical, having generally two hollow 

 tubercles on the posterior angles of the aperture. 



10. Plustra? lineata. Professor Jameson. 

 Hab. On rocks, shells, seaweeds ; common. 



This species spreads Hke a Lejyralia, in round, and often 

 in irregularly-shaped, patches. The cells are oval or ob- 

 long, sometimes with short stout spines, that meet across 

 the cell very like Lejjralia nit'ida, except that they are never 

 joined. At other times the spines are long and shaggy, 

 covering the cell ; but instead of uniting, inclining towards 

 the mouth, as we may call it, of the cell, where, in the 

 outermost cells, the spines are so lolig as to form a kind of 

 bushy beard. Several distinguished naturahsts are disposed 

 to think that this is not a distinct species, but a pecuHar 

 state of L. nitida or L. ciliata. I remember suggesting 



2 A 



