GEOLOGY OF FOLKJiSTONE — THE GAULT. 
395 
and Lamark, who of course classed iliem with tlie cephalopods ; Par- 
kinson, who considered theiv spathose structure as due to fossil- 
ization; Schlotheim, Ferussac (1822) and J. S. Miller, who in 1823 
read a paper before the Geological Society of London, specifying the 
natui'c of the Belemnite and its position in the animal, considering it 
analogous to the bone of the sepia, but according that priority of in- 
formation which was due to M. de Blainville. 
We now hand o\ir readers a list of the classification of the cepha- 
lopods, and shall then proceed to describe more particularly the 
natural characters of the divisions which are essential for a proper 
knowledge of the beautiful fossil forms of the Gault. 
CLASS, CEPHALOPODA. 
Order I. — Dibranchiata = Acetabulifera. 
Section, I. — Octopoda = 8 arms. 
Family 1. Argonautidce, 
2. OctopodidcB. 
Section II. — Decapoda. 
3. Teuthidw. 
4. Belemnites. 
5. Sepiadw. 
6. Spirulidce. 
Order II. — Tetrabkanchiata = Tentaculifeka. 
Section I. — Nautili. 
Family 1. Nautilidce. 
2, Orthoceratidw. 
Section II. — Ajvimonites. 
3. Artimonitidce. 
Where the ornamentation of a class of shells is so various and in" 
tricate as in the Ammonites, it becomes necessary to classify, as fai* 
as possible, the general characters of the kirids of patterns or methods 
on which the ornamentations are based. In the Ammonites these 
variations are at once apparent and distinct ; we see some with keels ; 
some with channels, or furrows along the back ; some with the backs 
square ; some rot\nd ; some sharp and others crenated ; and these 
again in varied stages, and susceptible again of minor divisions. 
Quenstedt, whose work is generally taken as the basis of the classi- 
fication of the Ammonites, has thus divided them — an arrangement 
which has been adopted by Mr. S. P. Woodward. 
