of the falling of this dust to the Geological Society.

[4] So named according to Patrick Symes's nomenclature.

[5] See Encyclop. of Anat. and Physiol., article Cephalopoda

[6] Mr. Horner and Sir David Brewster have described
(Philosophical Transactions, 1836, p. 65) a singular
"artificial substance resembling shell." It is deposited in
fine, transparent, highly polished, brown-coloured laminae,
possessing peculiar optical properties, on the inside of a
vessel, in which cloth, first prepared with glue and then
with lime, is made to revolve rapidly in water. It is much
softer, more transparent, and contains more animal matter,
than the natural incrustation at Ascension; but we here
again see the strong tendency which carbonate of lime and
animal matter evince to form a solid substance allied to
shell.

[7] Pers. Narr., vol. v., pt. 1., p. 18.

[8] M. Montagne, in Comptes Rendus, etc., Juillet, 1844; and
Annal. des Scienc. Nat., Dec. 1844

[9] M. Lesson (Voyage de la Coquille, tom. i., p. 255) mentions
red water off Lima, apparently produced by the same cause.
Peron, the distinguished naturalist, in the Voyage aux Terres
Australes, gives no less than twelve references to voyagers
who have alluded to the discoloured waters of the sea (vol.
ii. p. 239). To the references given by Peron may be added,