170 
pared it. This fibrous coat is so much produced beyond 
the apex of the chambered cavity upon an axis, (or elon- 
gated nucleus which probably existed in the ovum,) that 
it often forms the largest portion of the shell: in this 
circumstance principally it differs from Orthocera, the 
genus next akin to it. The genuine fossil Orthocere 
(no fossil Orthocera is given by Lamarck) have, more- 
over, a central siphuncle ; and were, at least some spe- 
cies, external shells. A few fossils hitherto referred to 
that genus, would deservedly arrange under an interme- 
diate one. 
Much has been written about the nature of the aatisan 
of which the Belemnite formed a part. The opinions 
of Platt and Miller agree, as far as they suppose. it to» 
have inclosed the shell by two lobes curved round it so. 
as to meet ina line along the front: the smooth surface, 
showing the impression of ramose veins in many species, 
and fibrous structure of the external coat, in which it 
resembles Cyprza, greatly favour this opinion. 
Lamarck, justly considering the chambered cone very 
similar to the genus Nautilus and Spirula, the animals of 
which were known to resemble Sepia, has placed Belem- 
nites, Orthocera, Nautilus, and all the chambered shells, 
with Sepia in the fourth order of Mollusca, the Cephalo- 
poda, and appears to consider the Belemnite an internal 
shell. This opinion is supported by all later authors, and 
by Mr. Miller, as far as regards the form of the animal. 
M. de Blainville, the last writer upon the subject, thinks 
with Cuvier and Lamarck, that the shell was internal 
like the hard substance called bone in the Sepia offici-. 
nalis, and brings forward two fossils of intermediate 
