85 
ORTHOCERA cordiformis. 
TAB. CCXLVIL 
Spec. Char. Obconical ; base contracted ; sides 
convex ; aperture round. 
In size and form this much resembles a bullock’s heart ; 
its septa are numerous, and placed directly across ; the 
surface appears to be smooth and plane ; the siphuncle 
is not quite in the centre; the tube of which it is com- 
posed is inflated into a globular form between each sep- 
tum (see figs. 2 and 3) ; the last chamber is narrower at 
its opening than at its base. 
If the Belemnites be really distinct from Orthocerae, 
the shortness of their alveoli will no longer be sufficient 
to distinguish them from Orthocerae, since the one before 
us is shorter than most of the genuine alveoli, and must 
still be considered as a true Orthocera, for it is not 
likely that a Belemnite, of a size proportioned to it, could 
have passed unnoticed, had it existed in the same quarry; 
and it is still less likely that it should have been de- 
stroyed, while its more tender chambered part remained 
so preserved as to resist the shock of worlds. I have 
been favoured with several specimens of this species by 
the same gentleman, and from the same place as the O. 
gigantea. One specimen is particularly interesting for 
shewing a section of the siphunculus, composed of a 
series of hollow globes : it is very much fractured, but 
there is enough of the outer part to prove that it belongs 
to this species, and not to the gigantea. A similar si- 
phunculus is described and figured by the Rev. Mr. 
lire ( a History of Rutherglen and Kilbride,” p. 306= 
