FLUSTRA. 351 
umberland, Miss Dale; Yorkshire and Orkney, Lieut. 
Thomas, R.N.; Stonehaven, Lady Keith Murray; Peter- 
head, Mr. Peach; Dublin Bay, M‘Calla; Leith and New- 
haven, on the fishermen’s nets, in some abundance, D. L., 
jun. 
This pretty little FYwstra bears considerable resemblance 
to I. avicularis, but the cells, which are larger and. more 
raised, are armed with more spines, and from various parts 
of the polypidom there are long tubular fibres thrown out 
to attach it to other bodies. It is often landed with bird’s- 
head appendages. 
*** Crustaceous. 
8. FLustra MemBRANAcEA, Shagreen Sea-mat, Lillis. 
Hab. On Laminarig, common. 
This forms a beautiful gauze-like incrustation on the 
broad frond of several seaweeds, but especially of Laminaria 
digitata. When it is upon a narrow frond I have seen it, 
though rarely, spreading itself a little beyond its support, 
and the portion that was free had cells on both sides. 
Young patches of it on the dark L. digitata are peculiarly 
beautiful, being of a pure silvery colour, with a gracefully 
rounded margin. The cells are quadrangular,—longer, how- 
ever, than broad,—with a blunt hollow spine at each angle. 
