;i74 ANlMy\L BELEMNO-SEPIA. 
that the Belemno-sepice,^ from which they were 
derived, attained great size. 
The fact of these animals having been pro- 
vided with so large a reservoir of ink, affords an 
a priori probability that they had no external 
shell ; the ink-bag, as far as we yet know, being 
a provision confined to naked Cephalopods, 
f In 1829, I communicated to the Geological Society of Lon- 
don a notice respecting the probable connection of Belemnites 
with certain fossil ink-bags, surrounded by brilliant nacre, found 
in the Lias at Lyme Regis. (See PhiL Mag. N. S. 1829, p. 388.) 
At the same time I caused to be prepared the drawings of fossils, 
engraved in PI. 44", which induced me to consider these ink- 
bags as derived from Cephalopods connected with Belemnites. 
I then withheld their publication, in the hope of discovering 
certain demonstration, in som.e specimen that should present 
these ink-bags in connection with the sheath or body of a Be- 
lemnite, and this demonstration has at length been furnished by 
a discovery made by Professor Agassiz (October, 1834), in the 
cabinet of Miss Philpotts, at Lyme Regis, of two important 
specimens, which appear to be decisive of the question. (See 
Pi. 44^ Figs. 7, 9.) 
Each of these specimens contains an ink-bag within the ante- 
rior portion of the sheath of a perfect Belemnite ; and we are 
henceforth enabled with certainty to refer all species of Belem- 
nites to a family in the class of Cephalopods, for which I would, 
in concurrence with M. Agassiz, propose the name of Belemno- 
se^na. Such ink-bags are occasionally found in contact with 
traces of isolated alveoli of Belemnites : they are more frequently 
surrounded only by a thin plate of brilliant nacre. 
The specimen (PI. 44", Fig. 1,) was procured by me from 
Miss Mary Anning in 1829, who considered it as appertaining 
to a Belemnite. Near its lower end we see the lines of growth 
of the horny anterior sheath, but no traces of the posterior cal- 
careous sheath ; within this horny sheath is placed the ink-bag. 
The conical form of this anterior chamber seems to have been 
